5th ANNUAL
ENGINEERING
GRADUATE STUDENT
SYMPOSIUM
BOOK OF ABSTRACTS
October 23, 2004
University of Michigan
Department of Mechanical Engineering
Ann Arbor, MI
``
5th Annual Engineering
Graduate Student Symposium
OCTOBER 23, 2004
BOOK OF ABSTRACTS
Organized by:
Department of Mechanical Engineering
http://me.engin.umich.edu
Department of Biomedical Engineering
http://www.bme.umich.edu
Symposium Organizers (ME , BME and KAIST):
Bryon J Sohns
Grant M Reeves
Amit Dhingra
Sanghum Baik
Gerald I Fernandes
Sangati Seth
Harish Narayanan
Honghai Zhu
Linda Chow
Junsok Jee
Yonggyun Yu
Advisor:
Professor Arvind Atreya
``
Jeffrey A Meganck
Vinod K Natarajan
Jianpeng Yue
Laura Elgas
Alisha B Diggs
Adrianne L Prysock
Dhruv Sud
Ruth R Cheng
Jeung Hoon Lee
Jun Youn Lee
Hyun Jun Shin
Sponsored by:
http://www.bme.umich.edu/
http://www.kaist.ac.kr/
http://www.engin.umich.edu
``
Schedule of Events
Saturday, October 23, 2004
8:15-9:00
Registration
9:00-11:30
Morning Sessions
Dynamics, Systems and Controls – EECS 1200
Design and Manufacturing – EECS 1311
Design and Manufacturing – EECS 1500
Fluid Mechanics and Heat Transfer – EECS
1001
Solid Mechanics and Materials – EECS 1003
Biomechanics – EECS 1303
11:30-12:00
KAIST Presentation
12:00-1:00
Lunch & Posters
1:00-1:30
Lawrence Livermore National Labs Presentation
1:30-4:00
Afternoon Sessions
Dynamics, Systems and Controls – EECS 1200
Dynamics, systems and Controls– EECS 1311
Design and Manufacturing – EECS 1500
Fluid Mechanics and Heat Transfer – EECS
1001
Materials and Biomaterials – EECS 1003
Joint Biomedical Engineering Session – EECS
1303
4:30-5:00
``
Awards
Presentations
Dynamics, Systems and Controls
Chair: Sanghum Baik
Session I A - EECS 1200
Gi-Hun Yang
17
Study of Human Tactile Perception Characteristics Using an Integrated Tactile Display System
Jing Zhou
Range Policy of Adaptive Cruise Control Vehicles for Improved Flow Stability and String
Stability
18
Burit Kittirungsi
Modeling of the HMMWV for advanced hybrid and power-train studies
19
Jongchul Jung
Observer Design with Stochastic and Deterministic Robustness
20
Ardalan Vahidi
Explicit and Implicit Load Governors for Constraint Management of a Fuel Cell Air Supply
System
21
Chair: Jeung Hoon Lee
Session II A – EECS 1500
Bryon Sohns
Determining Model Accuracy as a Function of Inputs and System Parameters
22
Dongsoo Kang
23
Creation of Milliken Moment Diagrams Using Time Integration of Controlled Dynamic Vehicle
Models
Ashish Deshpande
A Framework for Physical Cooperation Among Robots for Mobility Improvement
24
Young-Chul Choi
Detection of Bearing Fault Signal in Noise
25
Jeung-Hoon Lee
A mathematical model of pneumatic vibration isolator
26
``
BoHa Lee
Design of the Electromagnetic Actuator with Permanent Magnet for the High Efficiency and
Small Size
27
Chair: Sanghum Baik
Session II B – EECS 1200
Andreas Malikopoulos
Intergraded Starter Alternator (ISA) in a Hybrid Propulsion System
28
Denise McKay
Development and Validation of a Real Time Estimator for Fuel Cell Membrane Humidity
29
Kyungwon Suh
Power control strategy for fuel cell electric hybrid vehicle
30
Chia-Jui Chiang
Steady-State Multiplicity and Stability of Thermal Equilibria in Homogeneous Charge
Compression Ignition (HCCI) Engines
31
Jinming Liu
Power Train Analysis and Control for Hybrid Electric Vehicle Toyota Prius
32
Design and Manufacturing
Chair: Jianpeng Yue
Session I A – EECS 1311
April Bryan
Compliant analysis with consideration of welding distortions
33
Andres Clarens
34
Comparison of vegetable and petroleum base oils in metalworking fluids using the tapping torque
test
Farhad Ameri
Digital manufacturing market: the IT infrastructure for virtual manufacturing in distributed
environments
35
Chino Imediegwu
Compliant part assembly modeling and dimensional variation diagnosis using designated
component analysis
36
Fu Zhao
A transport model approach for developing micro-filtration compatible metalworking fluids
37
``
Honghai Zhu
Swing arm design in micro internal combustion swing engine (micse)
38
Chair: Junsok Jee
Session I B – EECS 1500
Shingo Takeuchi
Design for product-embedded disassembly
39
Zhijun Li
Tolerance allocation in compliant multi-station assembly through variation propagation and
analytical target cascading
HyunSeok Choi
Reliability analysis by five-level doe method
40
Mohammed Shalaby
Design of heat-reversible snap fits for space frame bodies
41
Rahul Bagdia
Customer demand satisfaction in production systems: random correlated demand case
42
Geol Choi
Improvement of mechanism of automatic book punching and binding machine using axiomatic
design
Chair: Jianpeng Yue
Session II – EECS 1311
Karim Hamza
Vehicle crashworthiness design via equivalent mechanisms and crash mode matching
43
Luis E Izquierdo
Control of the assembly process
44
Jeremy Michalek
Preference coordination in engineering design decision-making
45
Yonggyun Yu
Development of a cad-based general purpose optimal design system and its application to
structural shape for fatigue life
46
Junsok Lee
Manipulation of micro/nano particle using nanotweezer
47
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Fluid Mechanics and Heat Transfer
Chair: Gerald Fernandes
Session I – EECS 1001
Timothy Jacobs
The Development of a Low-NOx, Low-Soot Diesel Engine Combustion Strategy
48
Jonathan Hagena
The Impact of Fuel Injection Pressure on the Combustion, Emissions, and Performance of a
Medium-Duty Diesel Engine
49
Alexander Knafl
Dual-Use Engine Calibration: Leveraging Modern Technologies to Improve PerformanceEmission Tradeoffs
50
Aristotelis Babajimopoulos
A Fully Integrated CFD and Multi-zone Model with Detailed Chemical Kinetics for the
Simulation of HCCI Engines
51
Ronald Grover
Transient spray cone angles in Pressure-swirl Injector sprays
52
Fu Zhao
Modeling of Porous Filter Permeability via Image-Based Stochastic Reconstruction
53
Session II – EECS 1001
Amit Dhingra
54
Direct modeling support to the development of compact fuel processor systems for PEM fuel cell
application
Jingjing Li
A Computational Study of Catalytically Assisted Combustion in a Stagnation Point Flow
55
Songtao Tang
Numerical modeling of radiative extinction of spherical diffusion flames under microgravity
conditions
56
Cheensu An
57
Flow and heat transfer analysis for the performance improvement of Cross-flow fin-tube heat
exchangers
Chan Kwok Leung Paddy
Thermal Management of Slab-Coupled Optical Waveguide Lasers (SCOWL)
58
Xiulin Ruan
Temperature-Dependent Luminescence Quenching in Random Nano Porous Media
59
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Solid Mechanics and Materials
Chair: Jun Youn Lee
Session I – EECS 1003
Jiayin Lee
Transient Solution of The Inhomogeneous Thermoelastic Contact Problem Using Fast Speed
Expansion
60
Jon Kadish
The Effect of Accretion on the Stress Field of Small Planetary Bodies
61
Kyoo-Sil Choi
Frequency Drops in Resonant Bending Fatigue Tests of Notched Crankshaft Sections
62
Yeonseok Choo
Hybrid Trefftz Formulation in Finite Element Method and its Application on Plane Elasticity
63
P.-C. Lin and S.-H. Lin
Microstructures and Failure Mechanisms of Spot Friction Welds in Lap-Shear Specimens of
Aluminum 6111-T4 Sheets
64
Chang Qi and Z.-D. Ma
65
Preliminary Studies on Buckling and Crashworthiness Design with Multidisciplinary Objectives
and Uncertainties in the System
Biomechanics
Chair: Adrianne L Prysock
Session I – EECS 1303
Jiro Doke
Dynamic Modeling of Karate Front Kick
66
Lisa C. Case
A Comparison of the Forward Fall Arrest in Healthy Young Men and Women
67
Jaebum Son
The Effect of Aging on the Muscle and Neural Control Delay
68
Jeongho Kim
Mathematical Modeling to Predict RV Function During Artificial Lung Attachement
69
Taeyong Kim
Mechanical Response Of The Extracellular Layers of Sea Urchin Eggs
70
Sachin Goyal
Structural Modeling of DNA Loops in Lac-Repressor
71
``
Ken Kozloff
72
Homozygosity for a Dominant Mutation in col1a1 Restores Bone Phenotype in Comparison to
Moderately Severe Type IV Osteogenesis Imperfecta Present in Heterozygous Brtl Mice
Jeff Meganck
Thrombospondin-3 Effects on Bone Structure and Function
73
Materials and Biomaterials
Chair: Linda Chow
Session I – EECS 1003
Himabindu Nandivada
Reactive Polymer Coatings
74
L. N. Luong and R. J. Patel
Spatial Control of Protein within Biomimetically Nucleated Mineral
75
Jun-Youn Lee
Ultrasonic Transmission Characteristics of Continous Casting Slab for Medium Carbon Steel
76
Sung-tae Hong
Effects of Impact Velocity on Crush Strength of Aluminum Honeycombs
77
Ji-Ho Lim and Seok-Bong Kim
High Speed Tensile Test for the Material Properties at the Intermediate Strain Rate
78
Kristen Mills
The Behavior of Plasma Oxidized Polydimethylsiloxane
79
Woosung Choi
A Study on Interfacial Delamination in Thin Film Structure by Pull Test
80
Joint Biomedical Engineering Session
Chair – Ruth Chen, Dhruv Sud, Alisha Diggs
Session I – EECS 1303
Konstantinos Varsos
Micro-device for manipulating and shaping cells in tissue engineering.
81
Kimberly Cook
82
An algorithm for design of power systems for single and multi-component devices: a case study
focusing on a MEMS environmental test monitor
``
Mohammad Reza Abidian
Nano-tubular structured conducting polymers for neural prostheses applications
83
Rebecca C. Booi
84
Quantitative Contrast Analysis of In Vivo Ultrasound Imaging: A Study with a Combined 3D
Ultrasound/Digital Mammography System.
Huzefa Neemuchwala
Entropic Graphs for Simultaneous Multi-image Registration and Atlas Construction.
85
Kiran. K. Pandey
86
Effects of acquisition parameters and reconstruction methods on the correction of motion and
susceptibility artifacts in fMRI.
Marwa J. Zohdy
Optical and ultrasonic monitoring of laser-generated intracellular contrast agents: initial cell
culture studies.
``
87
Posters
Dynamics, Systems and Controls
Bryon Sohns
Determining Model Accuracy as a Function of Inputs and System Parameters
88
Bin Wu
89
Using Neural Network Surrogate Models to Optimize the Valve Timings for a 2.4 Litter VVT
Engine
Byunghoon Ko
CT-free Cup Orientator Using Sensors In THR
90
Wan-Ho Cho
A Study on the Design of an Acoustic Actuator Based on the Singing Mechanism of Cicadas
90
Design and Manufacturing
Emanuel Almeida
Modular logic control for reconfigurable manufacturing systems
91
Christine Vehar
Closed-loop tape springs as fully compliant mechanisms - preliminary investigations
92
Jie Luo
Machining of elastomers
93
Hyunjun Shin
93
Development of 3d position tracking system using psd(position sensitive detector) sensors for
surgery
Scott Miller
Characterization of friction drilling process: force, torque, temperature, and material analysis
94
Zhenhua Huang
Optical methods for reconfigurable precision measurement
94
Chino Imediegwu
Compliant part assembly modeling and dimensional variation diagnosis using designated
component analysis
95
``
Karim Hamza
Vehicle crashworthiness design via equivalent mechanisms and crash mode matching
96
Mohammed Shalaby
Design of heat-reversible snap fits for space frame bodies
96
Fu Zhao
A transport model approach for developing micro-filtration compatible metalworking fluids
97
Jeremy Michalek
Preference coordination in engineering design decision-making
97
Shingo Takeuchi
Design for product-embedded disassembly
98
Fluid Mechanics and Heat Transfer
Kim Hyoun Jun
Numerical Simulation of Combustion Driven Oscillations in Gas Turbine
99
Cheensu An
99
Flow and heat transfer analysis for the performance improvement of Cross-flow fin-tube heat
exchangers
James Smith
100
Cycle-Resolved Charge Evolution Measurements In A Direct Injected Engine Using DoublePulse LIF
Meng-Ping Chang
100
Electrokinetic Pumps for Dynamic Actuation of Cochlear Implants during Surgical Insertion
Fu Zhao
Modeling of Porous Filter Permeability via Image-Based Stochastic Reconstruction
101
Xiulin Ruan
Temperature-Dependent Luminescence Quenching in Random Nano Porous Media
101
Aristotelis Babajimopoulos
A Fully Integrated CFD and Multi-zone Model with Detailed Chemical Kinetics for the
Simulation of HCCI Engines
102
Tershia Pinder
102
An Experimental Investigation of the Effect of Fuel Concentration on Nonpremixed Jet Flames
``
Melissa Chernovsky
103
Effect of Increase in CO2 Concentration on Radiative Properties of Unsteady Spherical Diffusion
Flames in Microgravity
Ronald O. Grover
Transient Spray Cone Angles in Pressure-swirl Injector Sprays
103
Biomechanics
Jiro Doke
Dynamic Modeling of Karate Front Kick
104
Jeongho Kim
Optimized Design of a Thoracic Artificial Lung Using Computational Fluid Dynamics
105
Hogene Kim
Human balancing strategy used by riding bicycle as slow as possible
105
Ken Kozloff
106
Enhanced Mineralization and Reduced Toughness in the Aging Brtl Mouse Model for Type IV
OI
Materials and Biomaterials
Ji-Hoon Kang
107
Analysis of Polymer Deformation in Nanoimprint Lithography by using Molecular Dynamics
Simulation
Woosung Choi
A Study on Interfacial Delamination in Thin Film Structure by Pull Test
107
Joint Biomedical Engineering Session
Chen Nelson
A 3D Dual-Transducer Ultrasound Technique for the Assessment of Vascular Flow using
Contrast Agent Imaging
108
Inamdar V. Munish
Stochastic Simulation of Biometal Binding to Protein Sensors
108
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Andrea Lo
The Effects of Low Frequency Ultrasound on Droplets and Bubbles
109
Huzefa Neemuchwala
Multi-image Registration and Image Atlas Reconstruction using Entropic
Graph Based Mutual Information Estimation
109
Sun Min Kim
Electrokinetic phenomena during electroelution from clinical sampling strips
110
Jungwoo Lee
Inverted Colloidal Crystals as a Tissue Engineering Scaffold
110
Yoko Kamotani
111
Microfluidic Immunoassays using a Braille Display for Computer-controlled Fluid Actuation
Jonathan W. Song
Endothelial Cell Culture Under Computer-controlled Flow in Microfluidic Channels
111
Rainer Ng
112
Effect of contraction-induced injury in young mice lacking superoxide dismutase or glutathione
peroxidase genes
Mohammad Reza Abidian
Nano-tubular structured conducting polymers for neural prostheses
``
113
Dynamics, Systems and Controls
Study of Human Tactile Perception Characteristics Using an
Integrated Tactile Display System
Gi-Hun Yang, Ki-Uk Kyung, and Dong-Soo Kwon
yanggh@robot.kaist.ac.kr
Keywords: tactile sensation, tactile display, kinesthetic force feedback, vibration, static
pressure
This paper investigates three experiments on human tactile sensitivity using an integrated
tactile display system. The device can provide vibration, normal pressure and lateral slipstretch motion, all of which are important physical quantities of sense texture. We
investigated three things: an efficient method of stimulating, limitation of surface
discrimination based on kinesthetic force feedback, and the effectiveness of combining
kinesthetic force feedback with tactile feedback. Seven methods were tested using the
following elements individually or in combination: kinesthetic force, normal static
pressure, vibration, active and passive shear and moving waves. A prototype specimen
and a stimulus were presented to all examinees via a tactile display. The examinees were
asked to nominate the most similar sample. The experimental results show that static
pressure is a suitable stimulus for displaying the micro shape of the surface, whereas a
vibrating stimulus is more effective for displaying a fine surface. We also compared the
sensitivities of active touch and passive touch. Although kinesthetic force feedback is
suitable for displaying the shape and stiffness of an object, the roughness display suffers
from a limited resolution. As a result, the methods of kinesthetic and tactile feedback are
applied concurrently to simulate physical properties while an object is being touched. The
integrated tactile display mouse is expected to give users a more realistic sense of touch
in a virtual environment; for example in online shopping, CAD or other tangible spaces.
We plan to develop a tactile display algorithm to realize physical quantities such as the
spatial period, amplitude and element magnitude of a texture. The algorithm will also be
applied to our system.
``
17
Dynamics, Systems and Controls
Range Policy of Adaptive Cruise Control Vehicles for
Improved Flow Stability and String Stability
Jing Zhou and Professor Huei Peng
jzhouz@umich.edu
Keywords: Adaptive Cruise Control, range policy, string stability, traffic flow stability
Adaptive Cruise Control (ACC) is designed to provide enhanced driving convenience and
comfort. Before ACC vehicles are deployed on a large scale, their string behavior and
flow characteristics need to be carefully investigated. Two of the most important
macroscopic behaviors of ACC vehicles are traffic flow stability and string stability.
An ACC range policy should be designed to satisfy such properties as improved traffic
capacity and flow stability, closeness to human behavior, insensitivity to velocity
variation, and so on. However it is shown that the conventional Constant Time-Headway
(CTH) policy and the range policy inherently used by human drivers always lead to flow
instability when the traffic is constrained. In this study a nonlinear range policy is
proposed. This quadratic policy is obtained through an optimization procedure with
traffic flow and stability constraints imposed, and it competes favorably with the CTH
policy, the range policy employed by human drivers and the Greenshields policy.
A complementary controller is then designed to implement the proposed range policy,
which is based on the sliding mode technique. The desired acceleration is synthesized
from the current acceleration, the range rate and the compound range error. String
stability condition is derived for this combination of range policy and control law.
A microscopic highway merging simulation is set up to verify the effectiveness of the
nonlinear controller to maintain the proposed range policy. Results show that stable
traffic flow is achieved by the proposed method, up to a significantly higher traffic
density, whereas congestion will occur if the CTH or a Gipps model based human driver
behavior is assumed. The companion control law proves to be effective in regulating the
inter-vehicle range and preserving string stability for the nonlinear range policy.
``
18
Dynamics, Systems and Controls
Modeling of the HMMWV for advanced hybrid
and powertrain studies
Burit Kittirungsi and Dr.Loucas Louca
This work mainly focuses on the modeling of the vehicle dynamics and drivetrain models
of the HMMWV vehicle, which are developed within the Vehicle Engine Simulation
(VESIM) environment, allowing easy evaluation of different vehicle configurations.
These models are developed mostly using the components library, which contains models
and sub-models previously used within VESIM. Proper models are always critical for
providing accurate predictions of vehicle performance as well as fuel economy.
The complete vehicle model is validated and the parameters are fine-tuned so the
performance agrees with the data collected from the actual vehicle. Then, the simulation
with different advanced engine models is evaluated. The result reveals a promising
benefit gained from using a new, high boost V6 engine. In addition, the Integrated Starter
Alternator (ISA) is added into the system to give mild hybridization, which further
improves the performances and provides quantitative insight into benefits of potential
modernization of this vehicle platform.
``
19
Dynamics, Systems and Controls
Observer Design for Stochastic and
Deterministic Robustness
Jong Chul Jung, Kunsoo Huh, and Jeffrey L. Stein
jongchul@umich.edu, khuh2@hanyang.ac.kr, stein@umich.edu
Keywords: Robustness, Observer, Stochastic Uncertainty, Deterministic Uncertainty
An observer design method for stochastic and deterministic robustness is developed so
that an observer is less sensitive to uncertainties in transient and steady-state. The
uncertainties include not only deterministic factors such as unknown initial estimation
error, round-off error, modeling error and sensing bias, but also stochastic factors such as
disturbance and sensor noise.
From a stochastic perspective, a small value in estimation error variance represents
robustness to the stochastic uncertainties. It is shown that the upper bound of the error
variance can be minimized by reducing the observer gain and by increasing the decay rate
of the observer. From a deterministic perspective, a small value in the L2 norm condition
number of the observer eigenvector matrix guarantees robust estimation performance to
the deterministic uncertainties.
In this paper, two design methodologies are developed for both the stochastic and the
deterministic robustness. One is a graphical approach to get a feasible region of the
observer gain determined by specified design constraints on the cost functions. The
observer gain selected in this feasible region guarantees the robustness in the observer
performance. The other is an optimization approach by solving an optimization problem.
The cost function is expressed as a weighted sum of the objective functions and its
constraint is expressed as the linear matrix inequality representing the quadratic stability.
Simulation examples demonstrate that it can provide the best estimation performance
between the stochastic and the deterministic robustness depending on the application
environment.
``
20
Dynamics, Systems and Controls
Explicit and Implicit Load Governors for Constraint Management
of a Fuel Cell Air Supply System
Ardalan Vahidi
avahidi@umich.edu
Keywords: Model Predictive Control, Reference Governors, Fuel Cell, Compressor
Surge
In fuel cell powered vehicles, a performance bottleneck is posed by the air supply system.
In a high pressure Proton Exchange Membrane (PEM) fuel cell, a compressor supplies air
to the cathode. The compressor itself consumes up to 30% of fuel cell generated power
and therefore its size has direct influence on overall system efficiency. A centrifugal
compressor is prone to surge or choke during load transients and is limited in the amount
of air it can provide to the fuel cell stack. The air supply system is susceptible to
saturation during rapid transients which are typical of a drive cycle. Measures need to be
taken to prevent issuing commands that result in constraint violation.
In this work we design load governors as add-on devices to the air supply control system
to prevent compressor surge and choke and avoid oxygen starvation in the cathode. A
load governor, added to the air supply control system, monitors the load transients and
filters them if necessary, to prevent constraint violation. In principle a load governor
design is based on some form of constrained optimization. To implement the load
governor in memory and chronometric constrained automotive microcontrollers, it is
desirable to reduce the online computational load as well as RAM and ROM storage. An
ideal load governor is not overly conservative, while requires minimal online
computational resource.
In this work we develop a load governor using two approaches. The first approach is
based on model predictive control and is referred to as implicit. The model predictive
controller solves a constrained optimization problem online and modifies the reference
accordingly. The second approach is based on fast reference governor and is referred to
as explicit. In the fast reference governor, a large portion of computations is carried offline, rendering the online part computationally less demanding. We discuss the
performance and computational requirement of each scheme.
``
21
Dynamics, Systems and Controls
DETERMINING MODEL ACCURACY AS A FUNCTION OF INPUTS
AND SYSTEM PARAMETERS
Bryon Sohns, Prof. Jeffrey L. Stein
bsohns@umich.edu
Keywords: Model Accuracy, Model Validation
Vital to the effectiveness of simulation-based design is having a system model of known
quality. Previous research introduced an algorithm called AVASIM for assessing model
validity systematically and quantitatively. AVASIM assess the accuracy and validity of a
model based on a specific input and set of system parameters. The purpose of this
presentation is to present a AVASIM-based methodology that defines a range of validity
of a model with respect to input and system parameter variations
Two illustrative examples are presented to explore the feasibility of the proposed
procedure. The first example analyzes a linearized version of a nonlinear transient
vehicle-handling model. This model’s accuracy and validity are evaluated with respect to
variation of two system parameters, resulting in a two-dimensional range of validity.
Then a complex nonlinear hydrogen fuel cell model is linearized in order to investigate
its accuracy and validity with respect to two input parameters. This again results in a
two-dimensional range of validity, but with respect to input rather than system
parameters.
The results agree well with what is expected for the various models based on knowledge
of the effects of linearization on model accuracy. The proposed algorithm for assessing
model range of validity is a promising tool for determining model quality and thus
potentially useful for simulation-based design.
``
22
Dynamics, Systems and Controls
Creation of Milliken Moment Diagrams Using Time Integration of
Controlled Dynamic Vehicle Models
Dongsoo Kang and Professor Jeffrey L. Stein
dskang@umich.edu
The Milliken Moment Diagram (MMD) is a compact presentation of the results
from a kinematically constrained vehicle test to assess the handling performance
capability of the vehicle. The MMD is the yaw moment versus lateral acceleration for
given vehicle sideslip and steering angle. Front and rear tire traction boundaries are
easily defined. The MMD is traditionally created in a physical experiment or from
steady-state vehicle model. This paper proposes a new procedure for creating MMD
using numerical time integration of a controlled vehicle dynamic model. More
specifically nonlinear dynamics models such as CarSim, are embedded in a control
structure that modulates the vehicle yaw moment to achieve a desired sideslip angle.
This control structure can be implemented in a control software such as Simulink and the
resulting system numerically integrated. This controlled dynamic system mimics the
effect of the constrained physical experiment.
MMDs based on a nonlinear vehicle dynamics models are compared with those
from simpler bicycle and 3-degree of freedom models showing that the understeer
coefficient is best predicted by the nonlinear model. A previously published MMD using
a superimposed stereotype transient vehicle maneuver creates stability and controllability
margins. These margins are easily generated and combined on the diagrams produced by
the new proposed procedure. The same vehicle dynamics model is used for both
generating the MMD and the superimposed transient response. In conclusion this
procedure allows the user to create an MMD from any existing vehicle models by simply
adding the necessary control logic as described within. This allows the user to evaluate
the effects of many nonlinear factors by simply including them or excluding them from
the vehicle models.
``
23
Dynamics, Systems and Controls
A Framework for Physical Cooperation Among Robots for
Mobility Improvement
Ashish Deshpande and Jonathan Luntz
adeshpan@umich.edu
Keywords: Mobile Robots, Mobility, Cooperation
A team of small, low cost robots instead of one large, complex robot is useful in
operations such as search and rescue, urban exploration, etc. However, the performance
of such a team is limited due to restricted mobility of the team members. We advocate
the idea that through physical cooperation between members, the team of robots can
improve its overall mobility, with the underlying philosophy of simplicity to minimize or
eliminate the need for addition actuation and communication for cooperation. We
propose to develop a generalized framework for the analysis and development of
cooperative maneuvers among multiple cooperating mobile robots. As a case study of
cooperative maneuvers, we start with the goal of improving the ability of a pair of robots
to cross a wide gap. We analyze the statics and dynamics of this maneuver to establish
rules for designing a linkage and to develop decentralized control laws to minimize
requirements such as ground friction and wheel torque. We demonstrate the working of
this system with a hardware implementation to prove that a simple, low cost system can
achieve improved mobility via cooperation. We then present ideas for a generalized
representation framework based on adaptations of concepts from cooperative
manipulation. This framework will provide us the means of analyzing and designing a
broad class of cooperative maneuvers including gap spanning, step climbing, and the
crossing of rough and/or slippery terrain.
``
24
Dynamics, Systems and Controls
Detection of Bearing Fault Signal in Noise
Young-Chul Choi, Choon-Su Park, and Yang-Hann Kim(s)
youngcc@kaist.ac.kr
Keywords: fault detection, bearing fault, minimum variance cepstrum
Various bearings are commonly used in rotating machines. The noise or vibration signals
that can be obtained from the machines often convey the information of faults and these
locations. The condition monitoring of bearings has received considerable attention for
many years, because the majority of problems in rotating machines are caused by faulty
bearings. Thus failure alarm for the bearing system is often based on the detection of the
onset of localized faults.
The early fault signal that is caused by a microscopic crack is commonly embedded in
noise. Therefore, the success of detecting a fault signal is completely determined by a
method’s ability to distinguish signal and noise.
In 1969, Capon[1] coined a maximum likelihood(ML) spectrum which estimates a mixed
spectrum consisting of a line spectrum, corresponding to a deterministic random process,
plus an arbitrary unknown continuous spectrum. The unique feature of this spectrum is
that it can detect a sinusoidal signal imbedded in noise. Our idea essentially comes from
this method.
In this paper, a technique, which can detect an impulse embedded in noise, is introduced.
The theory of this technique is derived and the improved ability to detect the faults in a
ball bearing system is demonstrated theoretically as well as experimentally.
The bearing fault period make it possible to detect the localization as well as the presence
of the faults. This is because the location (for example, inner race, outer race, and ball
element) of the fault determine the period of impulse train.
We have performed the experiments for automobile HUB bearings. After completing
experiments, we have taken the HUB bearing to apart, and then observed the fault. It is
noteworthy that we have detected 4 fault HUB bearings among the normal 12 HUB
bearings which are confirmed by the bearing company.
Experimental results show that the proposed technique is quite powerful in the detection
of fault in noisy environments. In other words, it is possible to detect faults earlier than
before by using this.
[1]
J. Capon, 1969, Proceedings of the IEEE, Vol. 57, No. 8, August, pp.1408-1419, High-Resolution
Frequency-Wavenumber Spectrum Analysis.
``
25
Dynamics, Systems and Controls
A mathematical model of pneumatic vibration isolator
Jeung-Hoon Lee and Professor Kwang-Joon Kim
olo@kaist.ac.kr
Keywords: Pneumatic vibration isolator, complex stiffness
A pneumatic vibration isolator is widely used in precision engineering
department, such as nano-scale measurements, optical experiments and semiconductor
manufacturing, since it can provide low stiffness and superior damping characteristics
which might vary with frequency and excitation amplitude. To better understand such a
device, several mathematical models had been proposed by earlier researchers. But, an
experimental data for their validation of the proposed model shows significant errors
which are caused by the nonlinear behavior of capillary tube and diaphragm, component
of the isolator. Thus, an analysis of fluid flow in the capillary tube was re-examined and
an extraction of complex stiffness of diaphragm was studied. The improved mathematical
model of pneumatic vibration isolator with the inclusion of the refined model of capillary
tube and the complex stiffness of diaphragm exhibits a quite good match with
experimental results. All the things mentioned above will be introduced during the
presentation.
``
26
Dynamic, System and Controls
Design of the Electromagnetic Actuator with Permanent Magnet
for the High Efficiency and Small Size
BoHa Lee and ChongWon Lee
bhlee@novic.kaist.ac.kr
cwlee@novic.kaist.ac.kr
Keywords: Electromagnetic actuator, Position estimator, Hall sensor
As a dynamic actuator for attenuating the engine-induced vibration transmitted to
passenger vehicle chassis or investigating the vibration transfer path of the vehicle, an
electromagnetic actuator, consisted of a runner, two stators and pairs of electromagnets
and permanent magnets, is developed. It features that it is compact to be fit into the
limited space and yet, it possesses high efficiency and wide frequency bandwidth for
effective control of engine vibrations in standard size passenger cars.
By using the permanent magnets in electromagnetic system, we can increase the
actuating force of the electromagnetic system and decrease the total amount of the power
consumption of actuator when it operates. In addition to that an electronic circuit device
is also developed such that the displacement between the electromagnet pair and the
target can be estimated from measurement of flux density of the installed permanent
magnet only. It is found that the resolution and frequency bandwidth of the displacement
estimator are about 3m and 0 to 4kHz, respectively.
The electromagnetic actuator with the permanent magnet is capable of attenuating the
vibration over the frequency range of 100 to 400Hz, which is satisfactory for applications
of interest. And it uses the 12V power supply for commercial use of the designed actuator
in vehicles.
``
27
Dynamics, Systems and Controls
Intergraded Starter Alternator (ISA) in a Hybrid Propulsion
System
Andreas Malikopoulos, Professor Dennis Assanis and Dr. Zoran Filipi
amaliko@engin.umich.edu
Keywords: intergraded starter alternator (ISA), fuel consumption, powertrain simulations
This study is motivated by the endeavor of improving the fuel consumption of a medium
tactical truck (FMTV). An Intergraded Starter Alternator (ISA) is modeled in Simulink
and a ruled based algorithm is developed operating as a power management control. A
previous Simulink based model of the medium truck including the driver model, engine,
drivetrain and vehicle dynamics is used as a platform for the simulation. The comparison
of the fuel consumption among the powertrain architecture with ISA, the parallel hybrid
powertrain architecture and the conventional one will be presented.
This study extends previous and ongoing work on physics based, integrated, advanced
powertrain simulations in order to include hybrid components and various hybrid vehicle
architectures.
The objectives are to:

Develop physics based models of propulsion components for Hybrid Powertrains
and integrate them with the Diesel Engine, Driveline and the Vehicle Dynamics to
generate the complete Hybrid Vehicle Systems Simulation.

Integrate hybrid components within the flexible simulation framework(s) suitable
for studies of in-vehicle transients, power management, fuel economy and
emissions potential of hybrids vehicles.

Support cross-cutting projects, such as target cascading optimization efforts, NVH
studies in and potential application of advanced powertrain tools in the virtual
proving ground.
The predictive simulation tools allow systematic evaluation of the fuel economy potential
of various hybrid concepts, thus facilitating decision making process and selection of
design. Integrated, feed-forward, flexible simulation allows optimization studies of
component sizes and development of optimal power management strategies
``
28
Dynamics, Systems and Controls
Development and Validation of a Real Time Estimator for Fuel
Cell Membrane Humidity
Denise McKay and Professor Anna Stefanopoulou
dmckay@umich.edu
Keywords: fuel cell, membrane humidity, estimation
Proton exchange membrane fuel cells (PEMFCs) chemically combine hydrogen and
oxygen to produce electricity, water and heat. As with all power systems, PEMFCs may
experience environmental extremes. Such widely varying operating conditions greatly
impact the control of cell humidification and water removal. Consequently, maintaining
an adequate cell water balance is critical to optimizing cell performance. The difficulty of
sensing humidity, combined with the importance of this variable motivates an estimator
design. To this end, this work develops, parameterizes and validates a model for
estimating cell electrode relative humidity in real time without expensive measurements
that require unrealistic stack instrumentation.
The ability of the membrane to conduct protons is linearly dependent upon its water
content. On one hand, as membrane water content decreases, ionic conductivity
decreases, observed by a decrease in the cell voltage. This decrease in efficiency results
in increased heat production which evaporates more water, in turn lowering membrane
water content, creating a positive feedback loop resulting in hot spots (membrane
damage). On the other hand, excessive water stored in the electrodes obstructs fuel flow,
resulting in cell flooding. In both cases, the water concentration in the electrodes is
important in optimizing fuel cell efficiency and reliability.
A model of the water vapor transport through the membrane of a PEMFC for different
electrode vapor concentrations was identified using mass conservation with temperature,
pressure, mass flow and relative humidity measurements. We demonstrate that this
lumped parameter model can be used to accurately capture the spatially averaged
phenomena under certain conditions. The functional relationship between the diffusion
coefficient and membrane relative humidity was experimentally calibrated for a 24 cell,
1.4 kW fuel cell stack. The experimental method devised for model parameterization is
simple and reproducible. In contrast, existing methods for identifying the critical process
parameters require extensive membrane conditioning and cell disassembly.
The cathode and anode outlet relative humidity were then estimated and compared with
experimental results. These results demonstrate the capability of the proposed estimator
in accurately predicting electrode exhaust relative humidity of both the cathode and
anode of a multi-cell PEMFC stack. Our estimation scheme may be used as a virtual
sensor for start-up diagnostics.
``
29
Dynamics, Systems and Controls
Power control strategy for fuel cell
electric hybrid vehicle
Kyungwon Suh and Anna Stefanopoulou
kwsuh@umich.edu
Keywords: PEMFC, electric hybrid vehicle, DC-DC converter, multivariable control
Proton exchange membrane fuel cells (PEMFC) are typically augmented with additional
electric energy storage devices such as batteries and ultracapacitors in vehicle propulsion
applications. The resulting hybrid system is essential for autonomy in startup and fast
power response. Overall efficiency of fuel cell can be maximized with reusable energy
captured in battery from regenerative braking.
System integration and control issues are associated with various propulsion power
configurations with the fuel cell stack, DC-DC converter and battery. Although many
power management strategies already exist, the electric (voltage and current) architecture
of the hybrid PEMFC vehicle is still under intense debate and investigation.
In this presentation the electric architecture of fuel cell hybrid vehicle and associated
control issues will be covered. We first present physic-based models that combine (i)
reactants supply dynamics of the fuel cell stack, (ii) power electronics of DC-DC
converter, and (iii) battery. We then formulate the multivariable controllers and finally
derive the optimal control design for various electric architectures of a hybrid PEMFC
vehicle. Our results provide insight on the fundamental system controllability and ability
to handle transient loading depending on the choice of the electric architecture.
``
30
Dynamics, Systems and Controls
Steady-State Multiplicity and Stability of Thermal Equilibria in
Homogeneous Charge Compression Ignition (HCCI) Engines
Chia-Jui Chiang and Professor Anna Stefanopoulou
cjchiang@umich.edu
Keywords: stability, HCCI, autoignition
The stability of the autothermic process governing the autoignition of HCCI
(Homogeneous Charge Compression Ignition) engines is analyzed in this work. We find
conditions under which steady-state multiplicity exists with stable, unstable, and limitcycle equilibria. This analysis is conducted taking into account the internal feedback
structure of the thermal autoignition dynamics. Specifically, HCCI autoignition timing
determines the combustion heat produced and is determined by the heat provided through
high internal exhaust gas recirculation from previous combustion cycle.
It is shown that the thermal equilibria are characterized by a simple returning map
consisting of two curves, namely the breathing temperature curve and the combustion
temperature curve. The returning map and the stability analysis of the multiple steady
state equilibria is confirmed with a high order dynamic nonlinear model that includes
manifold filling and composition dynamics.
The existence of multiple steady state temperature equilibria and their stability is very
important for controller design. For instance, this information clarifies how sensitive the
HCCI engine is and how easy it is to move from a stable equilibrium to an unstable
equilibrium region due to perturbations coming from model uncertainty and input
disturbances. The result in this work after verified experimentally will guide our future
efforts in defining the conditions for stabilization under limited information.
Our analysis is essential for understanding the HCCI engine operation and crucial for
controller design. With better understanding on the region of attraction of the multiple
equilibrium points, a robust controller for the HCCI engine can be developed.
``
31
Dynamics, Systems and Controls
Power Train Analysis and Control for Hybrid Electric Vehicle
Toyota Prius
Jinming Liu and Prof. Huei Peng
jinmingl@umich.edu
Keywords: Hybrid Electric Vehicle, Power Management Control, Control Optimization
Hybrid electric vehicle (HEV) has drawn more and more attention in recent years. Toyota
Prius, as the first HEV entered the US market, is still playing an important role. It has a
unique power split system design with a planetary gear set which makes it potentially
improvable. More degree of freedom is allowed to be provided into such system which
can be benefited with more sophisticated control strategy.
To analyze and optimize the possible power management control strategy, an integrated
Prius power train model is developed in Simulink (See figure 1). It consists of four parts,
vehicle data source, vehicle dynamics, power management controller, and other elements,
as highlighted in different colors. All initial conditions and parameters are defined in the
data source blocks and loaded before running the Simulation. The vehicle dynamic model
presents the planetary gear set power transfer relation. Necessary power components (e.g.
engine, motor, etc.) are simulated during the simulation process. The power management
controller is to be tuned in the optimized control strategy to operate the entire system.
Figure 1: Prius Power Train Simulink Model.
This study will focus on the power train modeling analysis and the power management
control. The vehicle simulation model, especially the power split and control parts, and
the driving performance will be presented.
``
32
Design and Manufacturing
Compliant Analysis of Aluminum
Intensive Frame Structures
A. Bryan
J. Hu
abryan@umich.edu
jackhu@umich.edu
Keywords: aluminum, arc welding, frame structures, variation analysis
Due to the high strength-to-weight ratio, availability and low cost of aluminum,
aluminum intensive frames have gained increasing use in the automotive industry. These
structures usually consist of extruded and stamped components that are arc welded
together. The high thermal and electrical conductivity of aluminum structures result in
non-linear stress distributions in the final assembly. This non-linear behavior often leads
to inaccurate predictions of final assembly deviations and gross errors in tolerance
analysis and synthesis studies when traditional rigid body and compliant methods of
analysis are used.
This research proposes a generalized model for the prediction of the final assembly
deviation of an aluminum structure once the incoming part variations are known. The
non-linear stress distributions of the aluminum structure are caused in a large part by the
heat generated during the arc welding process and the material properties of the
component. The resulting distributions are also dependent on assembly forces and
welding parameters.
Empirical data will be used to determine the factors that have the greatest influence on
the assembly deviation. These factors will be used to create a simplified model that
linearizes the relation between the incoming part variations and the final assembly
deviation. The sensitivity values obtained could then be used for tolerance studies of
these structures.
``
33
Design and Manufacturing
EXPERIMENTAL COMPARISON OF VEGETABLE AND
PETROLEUM BASE OILS IN METALWORKING FLUIDS USING
THE TAPPING TORQUE TEST
Andres Clarens and Steven Skerlos
aclarens@umich.edu, skerlos@umich.edu
Keywords: Metalworking fluids, vegetable base oils, EP additives, particle size, tapping
torque test
Traditional metalworking fluid (MWF) formulations have been associated with a number
of environmental and health concerns that have driven recent efforts to develop new
formulations based on alternative vegetable and ester based feed stocks. This study uses
the tapping torque test to compare the performance of five base oil feedstocks for MWFs:
naphthenic mineral oil, a 50/50 blend of naphthenic and paraffinic mineral oil, soybean
oil, canola oil (75% oleic content), and a TMP Ester. The five oils were tested as straight
oils, and as soluble oil and semi-synthetic MWFs, to understand the impacts of
emulsification on base oil performance. Machining performance was evaluated using a
modification to the standard tapping torque test (ASTM D 5619) previously established
by the authors. Over 25 tapping torque experiments were conducted for each test fluid to
ensure the statistical significance of our results. The results indicate that as straight oils
all vegetable based stocks perform significantly better than the mineral oils. This trend
holds, although is much less pronounced, after the vegetable stocks are emulsified into
soluble oil and semi-synthetic MWFs. The results also indicate that some vegetable oil
base stocks have a higher potential for lubricity than others, with data revealing that the
soy and TMP ester provide improved tapping torque efficiency relative to canola oil in
emulsified MWFs. Ongoing and future work will further develop these vegetable-based
formulations to withstand the operating conditions of the manufacturing environment.
Current work in emulsion stability under hardwater conditions shows that the vegetablebased fluids are more stable than mineral-based formulations. Separate experiments
indicate that vegetable-based surfactant packages are more compatible with
microfiltration than commercial mineral based alternatives. Microfiltration of MWFs
removes microorganisms, waste grease, and particulates so that the fluid can be recycled
and maintained at a high quality. Traditional fluids tend to foul filters, making the
process expensive, but the vegetable based alternatives foul filters less readily and could
make microfiltration of MWFs a more widely adopted practice in manurfacturing
settings. Future work in alternative extreme pressure additives that are non-chlorinated
and inherently benign will complement the current research in bio-base oils to yield
complete MWF systems that are environmentally preferable to existing option.
``
34
Design and Manufacturing
Ontology-based Data Modeling in Digital Manufacturing Market
Farhad Ameri and Professor Deba Dutta
amerif@engin.umich.edu
Keywords: product lifecycle management, manufacturing market, web ontology
Product development today is no longer an internal job performed thoroughly within the
four walls of a single company but it is accomplished through collaboration between
multidisciplinary and cross-functional teams distributed geographically. Internal
organization, together with suppliers and customers altogether form the product value
chain and -as the building blocks of the Extended Enterprise-they are all closely involved
in the design process. Success of product development projects is determined by the
ability to leverage the Extended Enterprise’s intellectual assets.
Product Lifecycle Management (PLM) is a business strategy that creates an environment
in which the intellectual assets are proactively captured, managed and reused.
One core concept of PLM is to make product definition information interoperable for all
participating agents throughout the product value chain. Data interoperability is a
complex problem because it deals with the data format rather than its carrier.
One solution for data interoperability problem is implementation of a neutral language for
data exchange which encodes the product information in the semantic level. If all
participating agents commit to a common language with shared conceptualization,
modeling style, vocabularies and taxonomies -which altogether form the semantics- then
data exchange would be much more efficient and at the same time, machine level data
interoperability would be enabled. This shared conceptualization is known as “ontology”.
Among several ontology languages available, Web Ontology language (OWL) is the
most widely used and accepted one. OWL is the ontology language of the Semantic Web.
This research is aimed at deploying an OWL-based ontology for representing product
manufacturing information and demonstrating an application of the deployed ontology in
the manufacturing market framework. Manufacturing Market is a market in which
manufacturing processes are the objects of trade. Digital Manufacturing Market is an
Internet-based market that its demand (product) and supply (process) pools are populated
by digital (ontological) descriptions of products and processes. To fulfill the
manufacturing requirements of product, there should be a mapping between product and
a set of processes which will form the supply chain of product. Given the huge number of
processes in the supply pool of the Manufacturing Market, matchmaking between product
and processes and formation of optimal supply chain would be a computationally
intensive process. The problem becomes more difficult as the complexity of products
increases. One promising approach to address this problem is automation. To enable
automation, machine agents should be able to automatically process and integrate
information.
``
35
Design and Manufacturing
Robust Designated Component Analysis of Multiple Fixture
Faults in Compliant Sheet Metal Assemblies
Chino Imediegwu, S. Jack Hu
cim@umich.edu, jackhu@umich.edu
Products made of compliant sheet metals are widely used in the automotive, aerospace,
and electronics industries. One of the paramount challenges for the assembly process of
such compliant parts is the assembly dimensional variation which affect end product
functionality, reliability and perceived quality. This is particularly true for compliant,
non-rigid parts because clamping, joining and part fixture operations during assembly
may introduce more dimensional variation as a result of deformation, springback
phenomena and fixture error. To this effect, various methods for analyzing or diagnosing
sources of dimensional variation have been developed with the aim of enabling quick
detection and localization of assembly process faults based on inline dimensional
measurements. Research activities in this area indicate that 70 percent of all dimensional
faults in automotive manufacturing assembly occur as a result of fixture faults.
Consequently, substantial fixture failure diagnosis with the potential to quickly detect and
correct fixture faults can significantly improve overall build quality and enhance
productivity. The integration of resources and methodologies have typically been effected
on the front end of product development in scenarios characterized by complex products
with complicated assembly processes such as the automotive industry. In such situations,
manufacturing firms have employed sequential validation techniques to approve
components, then subassemblies and finally the end product. This sequential process
validation approach is typically characterized by increased costs due to rework and
lengthened lead times. This research study seeks to improve designated component
analysis as an analytical method and then use it to evaluate, quantify and correct
dimensional variation in compliant sheet metal assemblies caused largely by fixture
faults. This method can then be utilized to ensure a significant reduction in product
validation time, cost and tool rework through out the assembly process.
``
36
Design and Manufacturing
Design Microfiltration Compatible Metalworking Fluids via
Transport Model Approach
Fu Zhao, Andres Clarens, and Steven Skerlos
fzhao@umich.edu
Keywords: Metalworking fluids, microfiltration, design for environment, transport model
Although metalworking fluids (MWFs) are widely used in machine tool industry as
coolants and lubricants, they are inherently susceptible to microbial growth and
contaminant accumulation which lead to potential occupational risks, deteriorated
performance and significant cost and environmental burden due to frequently disposal.
As a recycling process, microfiltration of MWFs has been shown to increase the
longevity and quality of MWFs, and reduce the environmental and occupational health
risks associated with MWF applications. Research is currently being performed to better
understand the transport of MWFs through microfiltration membranes, including
mechanisms of membrane fouling.
In this paper, a mechanistic model previously developed by the authors is extended and
utilized in the design of MWFs with higher flux. Three interdependent fouling
mechanisms (i.e., pore constriction, pore blocking, and surface film formation) are
mathematically modeled at the pore-scale to develop parameters that are meaningful to
describe the relationship between MWF formulation and microfiltration flux.
Specifically, pore constriction is mathematically modeled as a balance between
adsorption and desorption parameters, and pore blockages are modeled in the context of
queuing theory as a function of microemulsion particle size distribution and coalescence
probabilities. After demonstrating the validity of the model, the model parameters are
utilized as metrics to evaluate the impacts of different MWF formulations on flux. MWF
formulation parameters considered here include oil type (mineral or vegetable), oil
concentration, oil:emulsifier ratio, composition of emulsifier package, and hardwater ion
concentration. It is shown that the model parameters can be reasonably estimated from
empirical flux data, and that trends in these parameters can be utilized to formulate MWF
microemulsions with slow coalescence rate, low surfactant adsorption, low
adsorption/desorption equilibrium ratio, and smaller particle size. For the MWF
microemulsions investigated in this paper, these characteristics are achieved by
minimizing amounts of excess oil and surfactants, maintaining an oil:surfactant molar
ratio of approximately 0.5, and by choosing emulsifier packages that result in
microemulsions with greater repulsion between droplets. Moreover, it is shown that
hardwater stable, vegetable-based, MWFs with high flux can be developed. Such
formulations, in conjunction with microfiltration-based recycling, can be employed in
manufacturing operations to significantly extend the useful life of MWF systems, while
reducing their toxicity and life cycle greenhouse gas emissions.
``
37
Design and Manufacturing
Swing Arm Design in Micro Internal Combustion Swing Engine
(MICSE)
Honghai Zhu and Professor Jun Ni
honghai@umich.edu
Keywords: List the keywords covered in your paper - optional. (Use Arial 11)
A Micro Internal Combustion Swing Engine (MICSE) is a rotationally oscillating freepiston engine. A major design challenge in this kind of engine is the thermal seizure of
the swing arm, which is called piston in traditional engines. Instead of using piston rings
for combustion chamber sealing, a gap sealing mechanism is adopted in a MICSE. Due
to the temperature difference between the swing arm and the engine core in the thermal
steady state, the gap between them shrinks down to zero from the engine start-up state to
steady state operation and finally evolutes to a thermal seizure, in the case of the swing
arm and the engine core using the same material. Experimental observations verify the
existence of thermal seizure after operating the MICSE for a few minutes.
The objective of this research is to reduce the thermal efficiency loss due to leakage
while avoiding thermal seizure. To have a good understanding of the thermal seizure
problem, a steady state heat transfer finite element model is built in ALGOR FEA. Based
on the analysis of the finite element model, an exact description of the differential
thermal expansion can be obtained. Optimal geometry design and materials selection are
proposed as the solutions to the problem. Experimental results verify these proposed
solutions.
``
38
Design and Manufacturing
Design for Products Embedded Disassembly Sequence
Shingo Takeuchi and Professor Kazuhiro Saitou
stakeuch@umich.edu
Keywords: design for disassembly, design optimization, computer-aided design
Due to the increased amount of abandoned products, reuse and recycling after the end of
their useful life have been taken into consideration to not only conserve limited sources
but also alleviate adverse environmental impacts such as air/water pollution and
greenhouse gas emissions associated with materials production and manufacturing.
Increased regulatory pressure is another motivation for reuse and recycling. For example,
European Parliament passed the WEEE directive to regulate the material collection and
appropriate End-Of-Life (EOL) treatment. Under these circumstances, the trend toward
reuse and recycling motivated by regulatory and voluntary initiatives is increasing around
the world, and consequently, manufacturers are becoming responsible for EOL treatments
of their products.
Design for Disassembly (DFD) is a design philosophy that intends to design and
manufacture products so as to make the disassembly process easier. One of the main
goals of DFD is to design products that can be disassembled along a disassembly
sequence that maximizes the profitability of the entire disassembly process under
environmental considerations and regulatory pressures.
Products embedded disassembly sequence is introduced in our current research. The
concept is to embed desired disassembly sequences inside a product during
manufacturing and activate them at the disassembly process. To realize this concept, joint
features that utilize geometric contacts between components are used to fix components
instead of fasteners such as screws.
A design methodology for products embedded disassembly sequence is proposed to
embed a disassembly sequence inside a product. It takes as inputs a disassembly sequence
and product components with their geometries, and produces optimal product
configurations with joint features as Pareto optimal solutions. A multi-objective genetic
algorithm with geometry-based crossover, coupled with products embedded disassembly
sequence analyses is used to obtain Pareto optimal solutions to this problem, exhibiting
trade-offs among functional constraints, joint feature cost and the embedment of a given
disassembly sequence.
``
39
Design and Manufacturing
Reliability Analysis for Nonnormal Distributions
Using Multi-Level DOE
Hyun Seok Choi, Sang Hoon Lee, and Byung Man Kwak
hschoi@khp.kaist.ac.kr
Keywords: Reliability analysis, Nonnormal Distribution, DOE(Design of Experiments),
Level and Weight, Pearson system
The main task of RBDO(Reliability based design optimization) is to obtain reliability
efficiently and accurately, especially for structural systems which involves finite element
analysis or mechanical systems with large number of random numbers. Various methods
developed up to now such as first-order reliability method(FORM), second-order
reliability method(SORM), Monte-Carlo simulation and experimental design techniques
are still found not satisfactory for such applications. Experimental design technique is
one popular choice and taken up in this article.
Experimental design technique needs no derivatives and little computation as opposed to
the Monte-Carlo simulation. The reliability analysis for nonnormal distributions using the
three level DOE(design of Experiments) method was developed by Seo and Kwak in
2002. Although this method estimates only up to the first four moments(mean, standard
deviation, skewness, and kurtosis) of the system response function, the results and the
type of probability distribution determined by using the Pearson system are shown very
good. However the accuracy is low in case of nonlinear performance function and
sometimes, the level calculated is outside of the region in which the random variable is
defined.
In this article we suggest a modified three level DOE method to overcome these
weaknesses and to obtain optimum choice for 3 levels and weights to handle nonnormal
distributions. Furthermore we extend it to finding the optimum choice for 5 levels and
weights to increase the accuracy in case of nonlinear performance function. A systematic
procedure for reliability analysis is then proposed by using the Pearson system.
The proposed procedure of reliability analysis is applied to several examples containing
various nonnormal distributions. This shows that the proposed method is practicable with
very good accuracy and efficiency, regardless of the type of distributions.
``
40
Design and Manufacturing
Design of heat-reversible snap fits for space frame bodies
Mohammed Shalaby and Dr. Kazuhiro Saitou
mshalaby@umich.edu
Keywords: Snap-fit design, genetic algorithms, design for disassembly
Recent legislative efforts to reduce the environmental impacts of the entire life cycle of
the next generation automotive body structures, aluminum space frame bodies, have
increased the need for non-destructive and standard means of the separation of external
body panels from structural frames. Aluminum space frame bodies are considered to be
the next generation body structures due to its lightweight and improved rigidity; they are
also environmentally sound due to the improved fuel efficiency owing to its lightweight.
One of the challenges in improving the recyclability of an aluminum space frame body
structure is the clean separation of incompatible alloys used in various body components,
in particular, extruded structural beams and stamped external panels.
In the current aluminum space frame bodies, joining between the extruded beams and
stamped external panels is achieved using permanent joints such as self-piercing rivets
and resistance spot-welding. These permanent joints can only be detached destructively,
inevitably leaving residues of mating materials that prevent the “closed loop” recycling of
aluminum alloys. It is essential, therefore, to develop a joining method that allows easy,
non-destructive detaching at a desired time. In this research, the use of heat actuated
reversible snap fits for car frame/panel assembly is proposed. Snap-fit is a preferred
joining method because: no need of separate fasteners, easily assembled, can be
disassembleable, reduces overall product cost and makes the recycling process more
economic, and provides clean separation between frame and panel.
In the first stage, different designs of a joint (snap fit) shape, dimensions and location on
the panel for the disassembly process are analyzed using flat and square panel model. In
the second stage, the optimum location of these snaps on an automotive fender model,
meeting certain NVH requirements, is found using genetic algorithms. The snaps are
modeled as spring elements with stiffnesses obtained from the square panel model.
ABAQUS is used to find the fender natural frequencies and their corresponding mode
shapes.
``
41
Design and Manufacturing
Customer Demand Satisfaction in Production Systems:
Random Correlated Demand Case
Rahul R. Bagdia and Semyon M. Meerkov
rbagdia@umich.edu, smm@eecs.umich.edu
Keywords: end-to-end performance metric, customer demand satisfaction, due-time
performance, random correlated demand, finished good buffer, Markovian demand
A randomly demand-subjected Production – Inventory - Customer (PIC) system is
analyzed for calculating an appropriate end-to-end performance metric of the overall
system. This performance metric expresses the (prob)ability of the system to meet
random customer demand and is termed as the Due-Time Performance (DTP) measure.
There exist other suggested performance measures like production rate, average
inventory and production variance, which are significant and still pose computational
challenges. But all of them isolate the main driving force for any production system – the
“demand” or the “customer”, whose quality and timely satisfaction will finally govern the
plant economy.
The considered serial-assembly production system is characterized by unreliable
machines (with random up and down times), finite intermediate and finished good
buffering and correlated Markovian demands. The suggested analytical DTP calculation
is made when the system reaches the steady state (or stationary distribution in stochastic
sense) under two machine reliability models namely – Bernoulli and Exponential. An
analytical method for calculating DTP of a one machine production line is developed
first, followed by an iterative algorithmic extension for a more general case of M
machines serial line.
The study aims in bringing out the effect of the correlation amongst demands on the
overall system performance (including DTP and inventory) and is an extension of
previously reported work for random but IID (Independent and Identically Distributed)
demands. A novel comparison between the DTP of a production system, subjected to
Markovian and IID demand models is established, and a parameterization of the
correlation structure is suggested. This parameterization makes possible to study various
marketing control strategies to influence the correlation pattern between the demands to
raise the DTP and simultaneously lower the inventories.
At the same time, the analysis supports optimal decision making for buffer capacities and
negotiating shipment period with the customers for a desired high DTP.
``
42
Design and Manufacturing
Vehicle Crashworthiness Design via Equivalent Mechanisms
and Crash Mode Matching
Karim Hamza and Professor Kazuhiro Saitou
khamza@engin.umich.edu
Design of vehicle structures in order to achieve good crashworthiness is highly desirable
yet difficult task that faces vehicle designers. Driven by ethical responsibility,
government regulations and market competitiveness, vehicle designers strive to increase
the safety of their vehicles while maintaining cost efficiency. Unfortunately, design for
crashworthiness is a difficult and expensive task. The best designs are not always
obvious, for example, increasing the stiffness of the structure makes it strong but may
decrease the crash energy absorption thereby degrading the vehicle safety. It is crucial to
have thorough understanding of the pros and cons of design decisions in order to improve
vehicle crashworthiness. Existing tools for analysis fall under three broad categories:
i) experimental testing, ii) nonlinear finite element (FE) simulations and iii) surrogate
(approximate) models.
Experimental crash testing is very expensive and is rarely used except in limited studies
and final tests for vehicle certification. Nonlinear FE simulations using detailed models
provide good prediction of vehicle performance during crash. However nonlinear FE
simulations consume enormous computational resources and their results are often
confounded by numerical noise. Therefore designers often resort to approximation
techniques in conjunction with the detailed FE models. Different types of surrogate
models have been used in the literature in order to aid designers in their task. The two
major categories of such models are: i) abstracted functional approximations such as
polynomial response surface and neural networks and ii) physical approximate models
such as lumped masses connected by springs. The current research is dedicated to
developing better physical approximate models that avoid extra abstraction and allow for
recapturing the essence of the crash phenomenon.
This research models the collapse of the vehicle structure during crash using equivalent
mechanisms composed of rigid masses connected by prismatic and revolute joints that
have special nonlinear springs, which are tuned to mimic the behavior of collapsing
structural members. The proposed modeling scheme offers physically sound
approximation that retains the gross behavior (or crash modes) of real vehicle structures.
Preliminary results show success in providing insightful guidance to improving suboptimal designs at a vastly reduced computational effort compared to direct optimization
approaches.
``
43
Design and Manufacturing
Control of the Assembly Process
Luis E. Izquierdo, S. Jack Hu (Use Arial 14)
leiv@umich.edu
Keywords: Compliant and rigid body assembly corrections, Variation reduction and
Programmable tooling.
Traditionally to improve the product quality, manufacturing engineers concentrate there
effort on robust design to prevent variation (i.e. using slip planes), and production
engineers in variation diagnosis and corrections. A new approach has emerged based on
the use of programmable or adaptive tooling. This tool was originally introduced in the
assembly lines to increase the flexibility (assemble different type of products in the same
assembly line). Now using programmable tooling is possible to adjust locators and
clamps on a part by part basis, doing so, the assembly variation could be diminish, and
the process could remain in control (Statistical Process Control SPC definition of in
control).
The question that emerges now is: how to correct the part in order to reduce the final
variation. There are two main approaches, the first considering that the parts are rigid
bodies, and the second considering that they are compliant or deformable parts. In the
rigid body case, the variation due to the part or tooling is corrected by measuring the
parts position before they are assembled together. Then the correction is calculated based
on the deviation from nominal position, and finally the rectification is applied. In the case
of compliant parts the strategy is the same, but the way to determine the correction is
different due to the nature of the parts.
This presentation introduces a method to determine the assembly correction of
complaints parts, and doing so remain in the in control state. The method is based on an
accurate model of the assembly process, the parts (using FEM) and the capabilities of the
programmable tooling. The modeling is crucial because in complaints there are infinite
possible variations of the parts by deformations. Then the most common or important
variations have to be analyzed, and the necessary corrections have to be study for that
specific variation to achieve almost zero variation of the final assembly. In a real case
combining the modeling results with in line measurements on the assembly station pre
and after-assembly the correction could be accurately specified for every part. A case of
study present the capability of this process in which a combination of compliant and rigid
body corrections could achieve a perfect assembly.
``
44
Design and Manufacturing
Preference Coordination in Engineering Design Decision-Making
Jeremy Michalek, Fred Feinberg, and Panos Papalambros
michalek@umich.edu
Keywords: Preference Coordination, Analytical Target Cascading, Design Optimization,
Discrete Choice Analysis, Logit
Design optimization methodologies offer assistance to engineers in achieving product
performance objectives; however, in practice most design problems involve tradeoffs
among a set of competing objectives such as performance, cost, and marketability. It
remains an open question: “How can a designer best navigate these tradeoffs to select the
most preferred design, particularly when social and economic preferences conflict with
user preferences and the user population itself is diverse?”
Preference coordination draws upon the rich literatures in marketing, economics, and
psychology to model preference structures of individuals and groups and coordinate these
preferences with design models of engineering performance. The rigorous coordination
of these models assists the designer in making tradeoff decisions by providing usable
information about consumer preferences for product characteristics and price, economic
preferences of the producer, and societal preferences such as reduced environmental
impact. Use of preference coordination is demonstrated to improve profitability
substantially relative to disjoint decision-making. When coupled with models of
heterogeneous consumer preferences, manufacturing systems, and public policy models,
it can be used to design product lines and to study the effects of regulation policy on
design decisions for navigating the tradeoff between private and public preferences.
This talk focuses specifically on the coordination of marketing and engineering models
for decision-making in product development. Marketing and engineering design decisions
are typically treated as separate tasks both in the academic literature and in industrial
practice, and their interdisciplinary interactions are not well-defined. In this article,
analytical target cascading (ATC), a hierarchical optimization methodology, is used to
frame a formal optimization model that links marketing and engineering design decisionmaking models by defining and coordinating interactions between the two. For complex
products, engineering constraints typically restrict the ability to achieve some desirable
combinations of product characteristic targets, and the ATC process acts to guide
marketing in setting achievable targets while designing feasible products that meet those
targets. The method is demonstrated in the design of dial-readout household scales, using
real conjoint choice data and a parametric engineering product design model. Results
indicate that the most profitable achievable product can fall short of predictions based on
marketing alone, but well ahead of what engineering may produce based on original
marketing target specifications.
``
45
Design and Manufacturing
Development of a CAD-based General Purpose Optimal Design
System and Its Application to Structural Shape for Fatigue Life
Yonggyun Yu and Professor Byung Man Kwak
ykyou@khp.kaist.ac.kr
Keywords: optimization, CAD based, CORBA, Open I-DEAS, I-DEAS
An integrated optimal design software system for structural components has been
developed, interfacing existing commercial codes for CAD, CAE and Optimization.
Various previously developed software systems for optimal design have been analyzed in
terms of modularity and independence of analysis activities, flexibility of optimal design
formulation, user convenience and so on. They include specialized optimal design
software codes, optimization module imbedded in CAD software developed by CAD
developers, and optimal design software systems based on API of commercial CAD
software. The advantages of the CAD imbedded optimal design approach and those of
specialized optimal design software are taken to develop the system. A user can define
his optimal design problem in the user interface for problem definition in the CAD
control stage, where design variables are directly selectable from the CAD model and
various properties and performance functions defined. The commercial CAD API codes,
Open I-DEAS is used for the development. The resulting software is minimally
connected to CAD and CAE systems while keeping maximum independence from each
other. This assures flexibility and freedom for problem definition.
Fatigue life optimization is selected as a nontrivial application area. For stress history
and life calculation, ABAQUS and Fe-Safe are used and interfaced. As a specific
example, the shape design of a knuckle part of an automobile is performed, where the
minimum fatigue life over the material domain in terms of the number of cycles of a curb
strike are maximized under the constraint of not exceeding the current mass. The fatigue
life has been improved four times the initial life. The developed software is shown to
maintain the advantages of existing optimal design software systems while improving
independency and flexibility.
``
46
Design and Manufacturing
Manipulation of Micro/Nano Particle using Nanotweezer
Junsok Lee and Professor Soohyun Kim
jameslee@kaist.ac.kr
Keywords: CNT arm, Nanotweezer, Electrochemical etching, Length control
There have been many research results about the nanotweezer using carbon nanotube
because of its superior mechanical and electrical properties to the conventional material.
But, it is very difficult to find out the carbon nanotube having proper length for
nanotweezer and to attach a carbon nanotube on the substrate.
In this research, a new method is proposed to make a CNT(carbon nanotube) arm and to
control its length for a nanotweezer which can handle a sub-micrometer sized particle.
And also, it is shown to attach a particle using the nanotweezer which was made by the
tungsten tip and carbon nanotube.
The electrochemical etching method was used to control the length of the CNT arm by
cutting the carbon nanotube with arbitrary length and it is possible to monitor the process
through the current measurement. And also, we can enhance the fixation strength of the
carbon nanotube on the substrate with the current during the cutting process. We can
calculate the etch rate of the carbon nanotube from the etched volume and the amount of
applied charge. The carbon nanotube is successfully cut using this method in a CNT arm
of a nanotweezer
The nanotweezer is composed of two CNT arms and macro actuators such as a piezo
actuator. The attaching action of a particle is done under the direct view of an optical
microscope with the nanotweezer. We use a sub- m sized particle for the target particle
which is placed on a target particle holder. Since the diameter of the carbon nanotube is
about 100 nm , the overall process is done under the circumstance of an optical
microscope.
Compared with the previous researches about the nanotweezer, the separated substrate of
the nanotweezer, which is proposed in this research, has some advantages as followings.
It is possible to grip large particle because the gripping range of nanotweezer is not
confined due to the macro actuators. It is possible to use conducting material as the
substrate of nanotweezer and it is not necessary to deposit additional electrodes on the
substrate.
``
47
Fluid Mechanics, Heat Transfer and Combustion
The Development of a Low-NOx, Low-Soot Diesel Engine
Combustion Strategy
Timothy Jacobs and Prof. Dennis Assanis
tjjacobs@engin.umich.edu
Keywords: NOx-Soot Reduction, Diesel Premixed Combustion
Increased consumer demand for fuel efficient, low-polluting vehicles motivates
automobile manufacturers to explore the use of diesel engines as the primary power
source. The demand for fuel efficiency is satisfied by the lean combustion strategy, the
good fit for turbocharging, and the use of a high compression ratio in a diesel engine.
However, the heterogeneous mixture of a diesel engine creates challenges for satisfying
the demand of a low-polluting vehicle. The following presentation outlines the use of
new electronic technology to trigger low-soot and low-NOx combustion strategies in a
diesel engine, while still surpassing gasoline fuel efficiencies.
The new electronic technology enables key design parameters such as variable fuel
injection pressure, variable manifold boost pressure, and variable exhaust gas
recirculation rates. These key parameters provide opportunities for simultaneous
reductions in soot and NOx by attaining fully premixed combustion, and avoiding the
high-polluting diffusion phase of combustion. The use of high injection pressure to
quickly inject fuel, an advanced injection timing to ensure proper time for mixing and
evaporation, and a high EGR rate to inhibit the chemical energy release all assist in
achieving premixed compression ignition combustion, and soot and NOx emissions that
meet upcoming federal emission regulations.
``
48
Fluid Mechanics, Heat Transfer, and Combustion
The Impact of Fuel Injection Pressure on the Combustion,
Emissions, and Performance of a Medium-Duty Diesel Engine
Jonathan Hagena, Christos Chryssakis and Professor Dennis
Assanis
jhagena@umich.edu
Increasingly stringent emissions standards are forcing modern diesel engines to produce
fewer emissions than their predecessors. To meet these challenges, engine manufacturers
have developed highly advanced fuel injection hardware and software that precisely
controls the characteristics of the injection event. As the flexibility of these systems
increases, so does the complexity of utilizing them optimally at all engine operating
conditions. Thus a comprehensive understanding of the influence of fuel injection
parameters on diesel combustion is necessary.
This work explores the impact of fuel injection pressure on the combustion, emissions,
and performance of a medium duty diesel engine. The focus of this investigation is
primarily experimental in nature, but also uses numerical tools to aid in the explanation
of observed data trends. Experiments were conducted on a 6.0 L V-8 diesel engine
equipped with combustion diagnostic and emissions instrumentation. Numerical studies
are conducted with KIVA-3V, a multi-dimensional computation fluid dynamics
simulation. This tool generated spatially and temporally resolved temperature and
equivalence ratio data to provide insight into the combustion process.
Injection pressure was found to significantly impact combustion and emissions, while
having a lesser effect on performance. Higher injection pressures speed up the rate at
which fuel is prepared for combustion, thereby increasing cylinder pressure and the rate
of heat release. This leads to increased combustion noise; tripling the injection pressure
augments the engine noise by a factor of 7.7. Carbon monoxide emissions drop by a
factor of 1.8, while hydrocarbon emissions increase 1.7 times. The same injection
pressure increase causes NOX emissions to rise by a factor of 2.4 and soot emissions to
decrease 35.5 times. Engine performance trends with injection pressure are dependent
upon engine operating condition, but no differences greater than 8% are observed in fuel
consumption.
``
49
Fluid Mechanics, Heat Transfer and Combustion
Dual-Use Engine Calibration: Leveraging Modern Technologies
to Improve Performance-Emission Tradeoffs
Alexander Knafl, Dr. Zoran Filipi, Prof. Dennis Assanis
aknafl@umich.edu
Keywords: Diesel Engine, Fuel Efficiency (BSFC), Nitric Oxides (NOx), Soot, Engine
Control Strategy, Injection Timing, Split Injection
Modern diesel engines manufactured for production vehicle purposes are calibrated to
meet EPA emissions regulations. Many of the technologies and strategies typically
incorporated to meet these emissions targets compromise engine performance and
efficiency. As an example, injection timing strategy is usually very much dictated by the
need to limit the nitric oxide emissions rather than maximum efficiency. However, new
emissions-reduction technologies offer more flexibility and therefore could be used to
enhance engine performance and efficiency, while still keeping the emissions within
tolerable limits. Thus, this paper explores the performance-emissions tradeoffs on a
modern medium duty diesel engine and uses the newly acquired insight to propose dual
use strategies, e.g. a performance oriented injection timing schedule required for military
applications augmented with an advanced multiple injection strategy that minimizes the
emissions penalty.
A study was conducted on a production, medium-duty International V8 Diesel engine.
The engine was run over an AVL 8-Mode steady state test using the production
calibration and an optimized control scheme for power and efficiency. It was shown that
by properly controlling the engine’s fueling strategy and disabling the production exhaust
gas recirculation (EGR), significant improvements in power and efficiency were realized.
For the power optimized calibration scheme, lower levels of total hydrocarbon (THC),
carbon monoxide (CO) and particulate matter (PM) emissions were obtained, while nitric
oxide (NOx) emissions increased.
``
50
Fluid Mechanics, Heat Transfer and Combustion
A Fully Integrated CFD and Multi-zone Model with Detailed
Chemical Kinetics for the Simulation of HCCI Engines
Aristotelis Babajimopoulos and Professor Dennis Assanis
ababajim@umich.edu
Keywords: HCCI, CFD, Combustion, Chemical Kinetics, Mixing
Temperature gradients present in an engine cylinder due to heat transfer to the cylinder
walls have a great impact on the combustion process in the Homogeneous Charge
Compression Ignition (HCCI) class of engines. Numerical models have been able to
accurately capture these temperature effects on the combustion process for homogeneous
mixtures. However, to facilitate control and higher power density, some researchers have
deviated from truly homogeneous mixtures and looked to more elaborate ways of mixture
formation, such as Variable Valve Actuation (VVA) or Direct Injection. These
techniques can introduce significant composition stratification in addition to temperature
stratification in these engines. Modeling of this process becomes much more
complicated because both mixing and chemistry must be handled in a computationally
efficient way.
A modeling approach that fully integrates a CFD code (KIVA-3V) with a multi-zone
model with detailed chemical kinetics is introduced. At each computational timestep, a
multi-zone model provides the KIVA-3V with the necessary energy source terms for each
cell, by solving the detailed chemical kinetics for groups of cells (zones) with similar
properties.
The methodology is an extension of previous work in that it can now account for both
temperature and equivalence ratio (composition) gradients in the cylinder throughout the
whole cycle. In this direction, a method of tracking down the equivalence ratio in each
cell during combustion is introduced. One important consideration is how to actually
define equivalence ratio to adequately capture the spatial composition field throughout
the cycle. Validation cases were developed by solving the detailed chemistry in every
cell of a KIVA-3V grid. This allowed the validation of the chemistry model alone,
isolating the chemistry model from other KIVA-3V submodels. The methodology was
tested for several cases with varying initial temperature and equivalence ratio
distributions, showing good agreement with the detailed solutions, while providing
further insight into the effect of equivalence ratio distribution on ignition, burn duration
and emissions in an HCCI engine.
``
51
Fluid Mechanics, Heat Transfer and Combustion
Transient Spray Cone Angles in Pressure-swirl Injector Sprays
Jordan A. Snyder, Ronald O. Grover, Jr., Professor Volker Sick and
Professor Dennis Assanis
janyder@engin.umich.edu, rgrover@engin.umich.edu
Keywords: sprays, pressure-swirl, nozzle fluctuations
The transient cone angle of pressure swirl sprays from injectors intended for use in
gasoline direct injection engines was measured from 2D Mie scattering images. A variety
of injectors with varying nominal cone angle and flow rate were investigated. The general
cone angle behavior was found to correlate well qualitatively with the measured fuel line
pressure and was affected by the different injector specifications. Experimentally
measured modulations in cone angle and injection pressure were forced on a
comprehensive spray simulation to understand the sensitivity of pulsating injector
boundary conditions on general spray structure. Ignoring the nozzle fluctuations led to a
computed spray shape that inadequately replicated the experimental images; hence,
demonstrating the importance of quantifying the injector boundary conditions when
characterizing a spray using high-fidelity simulation tools.
``
52
Fluid Mechanics, Heat Transfer and Combustion
Modeling of Porous Filter Permeability via Image-Based
Stochastic Reconstruction
Fu Zhao and Professor Steven J. Skerlos
fzhao@umich.edu
Keywords: permeability, porous filter, stochastic reconstruction, image
To facilitate design of porous filtration system that are widely used in environmental
engineering and pollution prevention applications, it is highly desirable to have a model
that can estimate filter permeability based on filter characteristics. The current approach
relies heavily on empirical models using only bulk properties with parameters calibrated
based on time consuming experiments. It is well known that transport properties of
porous media can not be predicted without including pore-scale physics. Previous
research has indicated that it is possible to predict permeability of isotropic geophysical
porous media through a network model approach.
This research develops a methodology for producing a pore-scale, 3D computational
network model of porous filter permeability that is based only on the analysis of 2D
images of the filter matrix (e.g., acquired from photography or electron microscopy) and
first principles. The computationally reconstructed porous filter model retains statistical
details of porosity and its spatial correlations within the filter, and can be used to
calculate permeability for either isotropic or 1D anisotropic porous filters.
In the isotropic case, validation of the methodology was conducted using 0.2μm and
0.8μm ceramic membrane filters, for which it is shown that the image-based
computational models provide a viable statistical reproduction of actual porosity
characteristics. It is shown that these models can predict water flux directly from first
principles with deviations from experimental measurements on the order of experimental
error. In the anisotropic case, validation of the methodology was conducted using a
natural river sand filter. For this case, it is shown that the methodology yields predictions
of filtration velocity that are similar or better than predictions offered by existing
filtration models, while not requiring experimentally determined coefficients. It was
found for the sand filter that the deviation between observation and prediction
(approximately 20%) was largely due to swelling during image preparation, which can
likely be reduced using methods reported in the literature. Based on these results, it is
concluded that the computational reconstruction methodology is valid for porous filter
modeling, and given that it captures pore-scale details, it has potential applications in the
investigation of permeability decline under the influence of pore-scale fouling
mechanisms.
``
53
Fluid Mechanics, Heat Transfer and Combustion
Direct modeling support to the development of compact fuel
processor systems for PEM fuel cell application
Amit Dhingra and Professor Hong G. Im
dhingraa@umich.edu
Keywords: fuel processor, microscale, hydrocarbon reforming, modeling
In the new millennium, there is strong research interest in the development of power
generation devices based on hydrogen and other hydrocarbons. This stems from the fact
that the power density of hydrocarbons is up to 100 times more than conventional
batteries. Hydrogen also has a much better efficiency and emission performance.
Applications of these small micro power generators will be prominent in portable and
mobile devices such as cell phones, laptops, PDA’s etc. However numerous problems are
faced by these micro-scale heat devices. Reduction in size leads gives rise to heat loss
from the increased surface to volume ratio. Thus these devices need to be designed as
compact, integrated and heat efficient packages.
This presentation is an overview of how modeling provided direct support and guidance
to the design of the U of M micro-fuel processor system. Modeling of a fuel processor
was approached by two interlinked paths: detailed modeling of individual component and
the system integration. Details of both approaches will be discussed. Even though
modeling cannot replace experimentation as a primary method to obtain performance
data, it will be demonstrated that modeling helped reduce the design time and costs of the
complete design process appreciably. A brief account on the modeling results and design
challenges will be discussed. Strategies for alternates designs and improving the current
one will be presented as well.
``
54
Fluid Mechanics, Heat Transfer and Combustion
A Computational Study of Catalytically Assisted Combustion in
a Stagnation Point Flow
Jingjing Li and Hong G. Im
jingjinz@umich.edu
Keywords: computational combustion, catalytic reaction, stagnation flow
Combustion is an interdisciplinary science involving a wide range of length and time
scales associated with chemistry and transport processes. In traditional macro-scale
combustors, accurate description within combustion devices relies heavily on turbulence
and reaction term closure at the scales smaller than numerical resolution. Except for some
specialized applications, the effects of wall heat transfer and surface reaction have been
usually considered secondary effects in macro-scale combustion. While studying microcombustors may seem simpler for its smaller dimension, the increased surface-to-volume
ratio also implies that the surface heat transfer and chemical reaction are no longer
negligible. In the gas-phase premixed combustion, it has been well known that there
exists a minimum physical critical dimension (such as the gap size), called the quenching
distance. Due to the large surface-to-volume ratio, a substantial amount of heat loss to the
surface is expected in micro-combustors. Therefore, it is desirable to extend these limits
to enhance the operating range and overall combustion efficiency. A natural choice is to
utilize the catalytic reaction at the surface. Recently, chemical kinetic models involving
simple gaseous fuels on platinum or palladium surface have been developed by
elementary reactions on a molecular level, described into modified Arrhenius equation
forms including additional surface coverage dependence. It may be expected that the
existing kinetic data that have been validated against experimental results can be
extended in the micro-scale combustion studies without significant loss of accuracy.
To gain fundamental understanding of physical and chemical characteristics in microcombustors, in the present study numerical simulations are performed in a stagnationpoint flow combustor. The combustible mixture of methane and air is blown on the top
of the catalytic platinum made surface, forming a classical stagnation-point flow
configuration. This geometry represents a classical problem of combined
heterogeneous/homogeneous combustion subjected to flow straining, which is a key
parameter that governs the quenching and flammability limit. A one-dimensional
similarity formulation is derived with full consideration of detailed surface and gas-phase
chemical kinetic models. Parametric studies are conducted to investigate the effects of
inlet fuel velocity, equivalence ratio, heat loss on the combustion and extinction modes.
The results show that the presence of catalytic surface in general extends the range of
mixture flammability. Bifurcations between detached and attached flame regimes are
also observed, which may have a significant impact when the behavior is coupled with
unsteady oscillatory operating conditions. The results are expected to provide insight
into improving the overall combustion stability and efficiency of micro-combustors.
``
55
Fluid Mechanics, Heat Transfer and Combustion
Numerical modeling of radiative extinction of spherical diffusion
flames under microgravity conditions
Songtao Tang, Ramanan Sankaran and Hong G. Im
tangst@engin.umich.edu, hgim@umich.edu
Keywords: spherical diffusion flame, microgravity, radiation
The presence of buoyancy influences the characteristics of diffusion flames, mostly
because it modifies and complicates the convective diffusive transport processes which
affect the transport of thermal energy and reactants to and from the chemical reaction
zones. In addition, gravity introduces a degree of asymmetry into an otherwise symmetric
phenomenon. Microgravity environment furthest excludes impacts beyond combustion;
therefore a reasonable comprehension of flame characteristics in microgravity condition
will largely help us understand the essence of combustion process. Moreover, fire safety
is a major concern in spacecraft running processes, understanding of the quenching
mechanism of microgravity flames helps to improve fire safety in spacecrafts.
In this study, a one-dimensional spherical model is set up to study the transient ignition,
combustion, and extinction process for highly radiating diffusion flames. Detailed
chemical kinetic rates and transport properties are incorporated through the CHEMKIN
and TRANSPORT packages, and a Newton iteration scheme via the TWOPNT module is
used to obtain the steady solution of the boundary value problems. A stiff differentialalgebraic equations solver, DASPK, is also employed to find the transient flame
dynamics. In addition, a radiation model is applied and properly modified to study the
quenching mechanism of flames. Some preliminary results are presented and compared
with experimental measurements.
``
56
Fluid Mechanics, Heat Transfer and Combustion
Flow and Heat Transfer Analysis for the Performance
Improvement of Cross-Flow Fin-Tube Heat Exchangers
Cheensu An and Professor Dohyung Choi
ancheensu@kaist.ac.kr
Keywords: porous medium model, heat exchanger, computational fluid dynamics
The flow and the heat transfer about the cross-flow fin-tube heat exchanger in an outdoor unit of a heat pump system has been numerically investigated. Using the general
purpose analysis code, FLUENT, the Navier-Stokes equations and the energy equation
are solved for the three dimensional computation domain that encompasses multiple rows
of the fin-tube. The temperature on the fin and tube surface is assumed constant but
compensated later through the fin efficiency when predicting the heat-transfer rate. The
contact resistance is also taken into consideration.
The flow and temperature fields for a wide range of inlet velocity and fin-tube
arrangements are examined and the results are presented in the thesis. The details of the
flow are very well captured and the heat transfer rate for a range of inlet velocity is in
excellent agreement with the measured data. The flow solution provides the effective
permeability and the inertial resistance factor of the heat exchanger if the exchanger were
to be approximated by the porous medium. This information is essential in carrying out
the global flow field calculation which, in turn, provides the inlet velocity for the
microscopic temperature-field calculation of the heat exchanger unit.
``
57
Fluid Mechanics, Heat Transfer and Combustion
Thermal management of Slab-Coupled Optical Waveguide
Lasers (SCOWL)
Kwok Leung Chan and Kevin Pipe
klchan@umich.edu
Keywords: microscale, semiconductor laser, temperature, heat transfer
Temperature control of semiconductor lasers is important for device stability and
efficiency; carrier leakage and wavelength drift occur at high operating temperatures. In
this experiment, a 20m microthermocouple with 10mK accuracy is used to measure the
top and bottom surface temperatures of the laser under various operating currents and
optical outputs. The relation between the optical output and the temperature of the laser
is investigated. Femlab models are used to verify the measurements and predict the
importance of heat transfer by convection and radiation. The causes of surface
temperature variation are investigated.
Fig.1 - 2 thermocouples are placing on the laser ridge
map of Femlab model
Fig.3 – Top and bottom surface temperatures VS current
``
58
Fig.2 – Temperature
Fluid Mechanics, Heat Transfer and Combustion
Temperature-Dependent Luminescence Quenching in Random
Nano Porous Media
Xiulin Ruan and Professor Massoud Kaviany
xruan@umich.edu
Thermo-Optical bistability is a phenomenon in which certain parameters of a nonlinear
system have two or more stable states for some particular inputs, caused by the
temperature dependence of the optical properties, such as the absorption coefficient and
the luminescence quantum yield. Bistability has its applications in optical communication
(e.g., all-optical switches), optical computation (e.g., memories, logic systems), and
compact solid state lasers. Previously, thermo-optical bistability has been treated using a
macroscopic, lumped energy conservation equation.
In this study, the intrinsic thermo-optical bistability in the luminescence of a random,
crystalline nanopowder doped with rare-earth elements, is analyzed at the microscopic
level, by considering the transport, transition, and interaction of the basic energy carriers.
The four fundamental governing equations (Liouville equation for electrons, Boltzmann
Transport Equation for photons and phonons, and energy conservation equation for
combined carriers) are used, and the carrier interaction processes are developed, with the
temperature identified as the critical variable. Particularly, the multiphonon relaxation
process is highly temperature dependent, resulting in a luminescence quantum yield as a
nonlinear function of temperature. Additionally, the thermal conductivity is strongly
temperature dependent, enhancing the nonlinearity.
The set of equations are solved first using the effective medium treatment (equation of
radiative transfer), yielding the one-dimensional, coupled intensity and temperature
distributions in the nanopowder. The luminescence quenching and temperature jump (due
to the positive feedback of temperature), occurring with the increase (or decrease) of the
irradiation, are predicted. Although weakened by conduction, the spatial nonlinearities of
temperature, such as a large local temperature gradient, is also predicted.
To evaluate the validity of the effective medium treatment (a particle treatment), the
coherent wave treatment (Maxwell’s equations) is also made. The same set of equations,
in which the BTE for photons is replaced by the Maxwell’s equations, are again solved
for a one-dimensional geometry. Then the nonlinear effects (bistability and field
enhancement) are predicted. The results of this direct simulation is compared with the
effective medium treatment. The predicted results for the luminescence bistability are in
good agreement with the available and ongoing experiments.
``
59
Solid Mechanics and Materials
Fast Speed Expansion Technique For The Transient Analysis Of
Automotive Clutches
Jiayin Li and James R. Barber
jiayinl@engin.umich.edu
Upon clutch application, the steel disks are squeezed against the friction disks by
hydraulic pressure. Rotational speed of the steel disks is produced by friction between the
steel and friction disks. The overwhelming majority of the frictional energy is converted
to heat. Because the heat generation is non-uniform, it produces non-uniform
deformations in disks. These deformations affect the contact pressure distribution, which,
in turn, further affects the temperature distribution. Hence, a feedback process is
established. When a particular sliding speed, called the `Critical Speed', is exceeded, this
feedback process becomes instable, due to at least one of real part of the eigenvalues is
positive. This phenomenon is known as thermoelastic instability (TEI). Yi developed
custom software, named `Hotspotter', using the finite element method to solve the critical
speed of each model.
However, `Hotspotter' assumes that the sliding speed is constant, whereas the
actual engagement takes place at variable sliding speed, which probably is higher than the
critical speed initially, but falls below it finally. Because engagement occurs over a very
short period of time, detrimental high local temperatures may not be developed before the
sliding speed has fallen below the critical value. Therefore, it is necessary to solve the
transient behavior of the thermoelastic contact problem.
For a large-scale problem, transient simulation is extremely time-consuming. AlShabibi and Barber has developed a reduced order model by using a truncated
eigenfunction expansion to represent the temperature. The truncated eigenfunction series
contain only those terms corresponding to several dominant eigenvalues. However, when
the sliding speed falls below the critical speed, the eigenvalues tend to cluster together
and no subset can be regarded as dominant. At same time, all of the real parts of the
eigenvalues are negative and the stiffness ratio is large, in other words, the system is stiff.
Thus, it is also hard to solve the ITTEC problem by traditional numerical methods when
the sliding speed is below the critical speed. Zagrodzki has developed transient modal
analysis method (TMA) to solve the ITTEC problem for the whole speed range. In the
TMA method, the transient nodal temperatures are expressed in modal coordinates,
corresponding to the eigenfunctions of the corresponding homogeneous (unloaded)
problem. However, for the large-scale ITTEC problem, this method is time-consuming,
too.
To overcome this difficulty, we propose a new method based on the asymptotic
waveform evaluation (AWE). This method is referred to as fast speed expansion (FSE).
With the known eigenvalues and eigenfunctions at a limited number of sparsely speeds,
the FSE technique employs an efficient algorithm to interpolate and expand the
eigenfunctions and eigenvalues over a speed band. Consequently, the FSE method can
greatly reduce the transient problem computational time by dramatically reducing the
number of full eigenvalue solutions required.
``
60
Solid Mechanics and Materials
Stress Fields in Accreted Planetary Bodies
Jon Kadisha and Professors Jim Barbera and Pete Washabaughb
jkadish@engin.umich.edu
Keywords: Accretion, Asteroids, Comets, Moving Boundary, Residual Stress
Studying the stress fields of planetary bodies provides insight into their internal
properties and mechanisms for evolution. The stress fields of the terrestrial planets
(Mercury, Venus, Earth, and Mars), asteroids, and comets cannot be accurately
characterized using the typical elasticity analysis because these objects formed by
accretion (Weidenschilling 1997, 2000). During the accretion process, the object grows
by the continual deposition of particles onto its surface. As each layer of particles is
deposited on the surface, it loads and deforms the underlying material such that
subsequent layers are applied to an object that has a non-zero stress field. This non-zero
stress field, also called the residual stress, is present for all time such that if all tractions
and body forces were removed from the body, it would still be in a state of stress.
The analytical solution of a self-gravitating, accreted sphere with zero tractions whose
spin rate is allowed to vary during its growth is derived using small deformation theory.
The stress field of such an object consists of an inelastic component that is constant in
time (residual stresses) and a time varying, elastic component. Both must satisfy
equilibrium, but only the latter has to satisfy compatibility. The additional degrees of
freedom needed to solve for the residual stress field come from the accretion process
itself. The process dictates that not only must the surface be traction free, but also that all
six stress components must equal zero at the sphere’s surface.
This stress field is qualitatively different from that of a non-accreted body determined
using the usual elasticity analysis and is illustrated by comparing the failure mechanisms
of the two bodies. In an accreted body, the gravitational stresses are hydrostatic implying
that failure is strictly a result of centrifugal forces arising from the object’s spin. In a
non-accreted body, the gravitational stresses are not hydrostatic and are significant in
determining failure with the rotational stresses actually reducing the tendency for
disruption. These differences result in higher effective strengths for accreted bodies than
non-accreted bodies.
References
Weidenschilling, S.J. 2000. Formation of Planetesimals and Accretion of the
Terrestrial Planets, Space Science Reviews 92, 295-310.
Weidenschilling, S.J. 1997. The Origin of Comets in the Solar Nebula: A Unified
Model, Icarus 127, 290-306.
a
b
Department of Mechanical Engineering
Department of Aerospace Engineering
``
61
Solid Mechanics and Materials
Frequency Drops in Resonant Bending Fatigue Tests
of Notched Crankshaft Sections
Kyoo-Sil Choi and Professor Jwo Pan
ckyoosil@engin.umich.edu
Keywords: Resonant frequency, Fatigue test, Notch depth
Resonant frequencies of a resonant bending system with notched crankshaft sections are
obtained experimentally and numerically in order to investigate the effect of notch depth
on the drop of the resonant frequency of the system. Notches with the depths ranging
from 1 to 5 mm, machined by an EDM (Electrical-Discharging Machining) system, were
introduced in crankshaft sections at the fillet between the main crank pin and crank
cheek. The resonant frequencies of the resonant bending system with the crankshaft
sections with various notch depths were first obtained from the experiments. Threedimensional finite element models of the resonant bending system with the crankshafts
sections with various notch depths are then generated. The resonant frequencies based on
the finite element computations are in good agreement with those based on the
experimental results. The information on the frequency drop for a given notch depth
from the results in this investigation can be used as a guidance to infer the extent of
fatigue crack depths in the resonant bending fatigue tests of crankshaft sections.
``
62
Solid Mechanics and materials
Hybrid Trefftz Formulation in Finite Element Method and Its
Application on Plane Elasticity
YeonSeok Choo and Professor Byungchai Lee
Chooyeonseok@kaist.ac.kr
Keywords: Finite element method, Trefftz, plane elasticity, drilling degrees of freedom
Many researchers have tried to get rid of shear locking and improve the performance of
plane elements in various ways including reduced or selective reduced integration
techniques, assumed strain methods, hybrid or mixed methods, nonconforming mode
techniques, and so forth.
Jirousek developed hybrid Trefftz variational formulation based on the Trefftz’s
variational method and conventional finite element method. Element stiffness matrices
were made up by approximating the internal displacement field that satisfys governing
equations of plane elasticity problems in the domain of elements and the boundary
displacement field generally used in the finite element discretization independently.
Allman et al approximated the displacement field by quadratic functions in the element
domain to add drilling degrees of freedom to the linear triangular and quadrilateral
elements and then, they could improve the performance of the elements. And elements
that have drilling degrees of freedom also have an advantage of modeling because the
shell elements utilizing them as membrane parts have six degrees of freedom per a node
in 3-dimensional space.
We introduce efficient and accurate plane elements with drilling degrees of freedom
based on the hybrid Trefftz method. By variational formulation, hybrid Trefftz method
connects two independent displacement fields: the internal displacement field satisfying
governing equations of plane elasticity problems and the boundary displacement field
consistent at the inter-element boundaries. In this study, we derive element stiffness of
triangular and quadrilateral elements using hybrid Trefftz variational formulation which
is based on the total potential energy principle and boundary integrations for stiffness
matrices. At the same time, we approximate the boundary displacement field by Allman
type displacement field for drilling degrees of freedom. However, we can easily apply it
to arbitrary polygon elements because all the domain integrals are changed into boundary
integrals. With these plane elements, we performed a series of tests and got good results
in view of accuracy, convergence and robustness.
``
63
Solid Mechanics and Materials
Microstructures and Failure Mechanisms of Spot Friction Welds
in Lap-Shear Specimens of Aluminum 6111-T4 Sheets
P.-C. Lin, S.-H. Lin, and J. Pan
paicl@engin.umich.edu
Keywords: Spot friction welds, aluminum 6111-T4, microstructure, failure mechanisms.
Microstructures and failure mechanisms of spot friction welds in aluminum 6111-T4 lapshear specimens are investigated based on experimental observations. Two types of
tools, a Type I tool with a flat tool shoulder and a Type II tool with a concave tool
shoulder, were used to join the aluminum sheets with different processing parameters.
Optical micrographs of the cross sections of spot friction welds made by the two types of
tools in lap-shear specimens before and after failure are examined. These spot friction
welds show the failure mode of nugget pullout under lap-shear loading conditions.
However, the micrographs show different microstructures and failure mechanisms for
spot friction welds made by the two types of tools with different processing parameters.
The experimental observations suggest that under lap-shear loading conditions, the
failure is initiated near the stir zone in the middle part of the nugget and the failure
propagates along the circumference of the nugget to final fracture.
A schematic illustration of spot friction welding (SFW) process.
``
64
Solid Mechanics and Materials
Preliminary Studies on Buckling and Crashworthiness Design
with Multidisciplinary Objectives and Uncertainties in the
System
Chang Qi and Z.-D. Ma, N. Kikuchi, C. Pierre
cqi@ umich.edu
Keywords: Buckling,
Uncertainties
Crashworthiness,
Multidisciplinary
Design
Optimization,
In this presentation, we will consider fundamental principles of buckling and
crashworthiness design, especially with other design objectives (such as durability and
NVH) and uncertainties in mind. Uncertainties can be classified into three categories:
parameter uncertainties, modeling uncertainties, and uncertainties in the loading and
boundary conditions. Uncertainties will have great effects on the results obtained from a
deterministic buckling or crash analysis, and it may change the nature and fundamental
phenomena of the prediction. We will discuss this through examples. Another issue to be
discussed is the relationship between buckling and crashing. Buckling modes have been
used to design a structure for crashworthiness, but crashing is not equal to buckling.
Structure may fail under the load far below the critical buckling load. We will also
discuss this through examples.
In the study of vehicle crashworthiness, design of a structure against buckling failure is
an important issue. Desired critical buckling loads and buckling modes can be achieved
through design optimization including size, shape and topology; this will be the objective
of this research. Besides the stability target, durability and NVH targets can also be
included resulting in a multidisciplinary design optimization problem. Currently, design
against buckling (DAB) of a general purpose mounting system has been studied to
investigate the essences of the physical problem, considering the uncertainties mentioned
above. The general purpose mounting system can represent an engine mounting system
or a cabin-frame mounting system, etc. Multidisciplinary design optimization of a real
engineering application in an innovative hydraulic-hybrid vehicle is used as an example
to demonstrate the design targets mentioned above.
``
65
Biomechanics
Dynamic Modeling of Karate Front Kick
Jiro Doke, Professor Arthur D. Kuo
jdokeh@umich.edu
Keywords: karate kick, biomechanics, dynamic modeling
A front kick is one of the most common forms of kick in karate. From observation, the
hip and knee joint of the kicking leg go through a sequence of flexion and extension
phase. Previous experimental studies showed that, kinematically, the kick starts with hip
and knee flexion, then the knee starts to extend, and the hip extends slightly at impact.
However, it is not well known how this coordination of joints relates to the performance
of the kick, and whether this is the optimal sequence.
A rigid two-segment model was created to simulate a closed stance front kick. Torque
actuators at the hip and the knee obeyed a force-velocity relationship. These actuators
were activated with a constant level of activation during the flexion and extension phase.
We varied the levels of activation to examine the relative effect of each phase. For any
particular set of activation levels, we systematically simulated for various combinations
of two switch timings. The first timing was the time from the beginning of the kick to
when the knee torque switched from flexion to extension. The second timing was the
time from the first timing to when the hip torque switched from flexion to extension. The
simulation terminated when the knee angle reached the final configuration. For each
simulation, we noted whether the kick had terminated in the target area, which was a
range of about 10 cm around the hip height level. The horizontal foot velocity at kick
completion was used as the performance measure.
For some sets of knee activation levels, we found an optimal combination of the two
switch timings that resulted in the largest final horizontal foot velocity. It is interesting to
note that it is possible to perform a kick with only activating the hip torques and no knee
activation. The dynamic coupling of the segments allows the lower leg to move in the
desired trajectory. Adding some activation on the knee extension phase tends to increase
the foot velocity. The highest final foot velocity is achieved at a relatively low knee
flexion activation and high knee extension activation.
A qualitative look at one of the optimal kicks revealed that hip extension just before the
end of the kick increased the horizontal velocity of the foot. Such behavior can be
observed in a real kick, in which the deceleration of the thigh segment induces an
acceleration of the shank segment. The extension of the hip allowed the foot to be
thrusted forward. As the knee straightens, the foot velocity decreases, which suggests
that foot impact should occur before the knee is fully extended, ideally when the velocity
is at its local maximum.
``
66
Bio-engineering
A Comparison of the Forward Fall Arrest in Healthy Young Men
and Women
Lisa C. Case, Jia-Hsuan Lo, and James A. Ashton-Miller
lcase@umich.edu
INTRODUCTION: Falls and fall-related injuries will cost the United States $85 billion
by the year 2020 (Englander et al., 1996). Sixty percent of falls in older adults are in the
forward direction (O’Neill et al., 1994) and 96% of distal forearm fractures occur as the
individual attempts to arrest the fall with the upper extremities (Keegan et al., 2004).
While there have been studies on the mechanics of forward fall arrests in males
(DeGoede et al., 2002), there are no published studies describing the mechanics of
forward fall arrests in females. Older women have higher rates (1.2 to 2.2) of falls than
older men (Luukinen et al., 1994) and they are twice (1.8 to 2.2 times) as likely to sustain
an injury as men (Malmivaara et al., 1993). One factor that may contribute to these
statistics is the finding that women have almost 50% less upper body muscle strength per
unit body size than age-matched men (Metter et al., 1997).
METHODS: A preliminary study of 10 young healthy women was therefore conducted.
It was based on an earlier study in young men in the Biomechanics Research Lab at the
University of Michigan (DeGoede, 2002; Lo et al., 2003) in order to determine whether
gender affects how falls are normally arrested. The women were initially supported in a
standardized forward leaning posture with the shoulders either 70, 80 or 90 cm from the
ground. The subjects were then released and asked to arrest the forward fall by landing
with each hand on a force plate. Impact forces and body kinematics were recorded
during each fall arrest.
RESULTS: The impact force, normalized by body weight, was similar for both males
and females for a given fall height. However, the women adopted a different fall arrest
strategy than the men. While the initial elbow flexion angle at impact was similar for both
males and females, the change in elbow angle post impact was significantly smaller in the
women (~25% of the male average, P<0.05).
DISCUSSION: The smaller change in elbow angle in the women during the post-impact
“ride down” phase of the fall arrest may be attributed to their smaller upper extremity
extension strength compared to men (after normalization for body size). They adopted a
strategy that involved maintaining straighter elbows during the “ride-down” phase of the
fall arrest, apparently to prevent their elbows from buckling under the impact force and
their head or torso striking the ground. Lack of confidence in being able to arrest the fall
without injury might also accentuate this. Current exercise interventions tend to focus on
maintaining lower extremity strength, but there is less emphasis on upper body strength,
especially in women. Our results suggest that elderly women should try to maintain as
much upper body strength as possible.
``
67
Biomechanics
The Effect of Aging on the Muscle and Neural Control Delay in
One-Legged Balance
Jaebum Son and Dr. James Ashton-Miller
jaebum@engin.umich.edu
Keywords: biomechanics, muscle, control delay
Falls are one of the most common problems of older people which may cost mobility and
mortality, and it is believed that these happen because of the lack of balance ability in the
aging. However, no clear answer to this has been provided to understand the mechanism
of human balance yet. On the other hand, it was found clinically that one-legged balance
time has strong relationship with balance ability or falls, and researchers used this to
predict for the possible future falls. In this study, we show what could be significant
factors causing a larger balance sway during one-legged balance using control theory.
It was hypothesized that the velocity feedback compensates the neural delay and CNS
processing time effectively, and Fast Fourier transformation (FFT) and power spectral
density (PSD) are used to prove the existence of velocity feedback. The muscle
bandwidth was identified in the frequency domain as well. After that, the least square
optimization is used to simultaneously estimate the magnitude of the velocity feedback
and the delay.
10 young and 10 healthy old subjects volunteered for the experiment and signed the
consent form. Subjects stood on the force plates with their arms crossed, and at the signal
of examiner, they started one-legged balance up to 30 seconds maximum. Two AMTI®
force plates were used to measure the ground reaction force and OPTOTRAK was used
for the kinematic analysis. The displacement of the center of mass in frontal plane was
calculated with 4 segment model.
It was shown that the velocity feedback compensates the neural delay effectively. The
older group appeared to have a narrower muscular bandwidth. However, the older group
didn’t show a significant longer delay time over the young group. Rather, the sway
magnitude defined by the standard deviation of the normalized center of pressure
appeared to be significantly correlated with the amount of velocity feedback.
Previous studies have failed to prove the existence of velocity feedback in the system
dynamic analysis nor could they satisfactorily include the effect of neural delay in the
balance model, even though the biological experiments showed significant neural delay
and CNS processing time. This research explained the nature of human body sway and
provided a novel way to decouple the velocity feedback and neural/CNS delay that match
all previous neurophysiological results.
``
68
Bio-engineering
Mathematical Modeling to Predict RV Function During Artificial
Lung Attachment
Jeongho Kim, MS; Hitoshi Sato, MD; Ronald Hirschl, MD;Robert
Bartlett , MD ; Keith Cook, PhD
jeonghok@umich.edu
Thoracic artificial lungs (TALs) can, under certain conditions, lead to elevated right
ventricular (RV) afterload, dysfunction, and diminished cardiac output. The objective of
this research is to predict cardiac index (CI) during in-vivo TAL attachment with elevated
RV afterload using baseline, pre-attachment data. An MC3 BiolungTM, with integral
compliance chamber, was implanted in healthy sheep and sheep with pulmonary
hypertension. Results indicate that the change in ePSR (ΔePSR) is an effective index to
predict the percentage of the change in CI (%ΔCI) using the formula; %ΔCI = 0.00156
ΔePSR 2 - 0.0612 ΔePSR (R2 = 0.78). The ePSR depends on TAL resistance, natural lung
resistance, and anastomosis resistance, which vary with flow rate. To calculate ePSR and
CI using the baseline data, mathematical models must consider these resistances. The
TAL resistance is determined through in vitro experiment. The pressure drop across the
TAL was recorded under steady and pulsatile flow conditions, and is a function of flow
rate, heart rate and blood viscosity. Natural lung resistance can be measured as a function
of flow rate and baseline resistance, which clinically can be determined pre-operatively,
but care must be taken during TAL use to avoid changes in natural lung resistance due to
inflammation. Anastomosis resistance also can be determined by 1''×1/2''×1'' and
1''×5/8''×1'' T-connectors. Anastomoses resemble T junctions and thus develop fluid
mechanical, so-called “minor” energy losses due to a change of direction in the fluid
flow. Both 2.0 and 3.0 cP glycerol solutions were pumped through the TAL. Energy loss
per unit volume across some components differs from the measured pressure drop due to
Bernoulli effects. In some cases results are presented in terms of mechanical energy loss,
in other cases it is more convenient to leave results as measured pressure drops. In vitro
experiments showed that the pressure drop at the TAL inlet anastomosis was the most
significant anastomotic pressure loss. All anastomotic pressure drops to and from TAL
and pulmonary artery are modeled as a function of pulmonary artery and TAL inlet graft
diameter, cardiac output, blood viscosity, and heart rate.
``
69
Biomechanics
Mechanical Response Of The Extracellular Layers of
Sea Urchin Eggs
Taeyong Kim, Chia-Wei Wang, Leslie Lamberson,
and Professor Ann Marie Sastry
taeyongk@umich.edu
Keywords: jelly coat, sea urchin, echinoid, inverse finite element method,
fluid solid interaction
The transparent, extracellular layers surrounding the eggs of the sea urchin Arbacia
Punctulata account for approximately 3-11% of maternal energy in egg production, and
thus likely play an important role in successful fertilization of this free-spawning
organism.
A shear flow experiment was used to simultaneously deform the egg and jelly layer by
causing shear stresses the eggs. The peeling away of egg jelly was observed at the
lowest flow rate (3.42 x10-6m3/sec) during the experiment. Egg rupture was also observed
at higher flow rate (7.42 x10-6m3/sec) during the experiment.
The egg and jelly layer exhibited nonlinear behavior under external loads. The simplest
hyperelastic model, the Neo-hookean model, was adopted to model their behaviors.
Material properties of the egg and jelly coat were found using an inverse finite element
method (IFEM) approach involving a fluid-solid interaction scheme.Shear flow produced
stresses on the surface of the egg or jelly layer which satisfied the universal deformation
condition due to traction, under assumptions of an isotropic, homogeneous material. The
shear modulus of the egg was in the range of 110-160 Pa. However, the shear modulus
of the jelly layer varied among the eggs. Some jelly coats had a shear modulus close to
that of the egg, while some had 48 – 64 Pa. These differences may be due to interactions
between the jelly coat and seawater, decreasing the jelly coat strength over time.
Future work will be focused on the relative importance of the jelly coat’s protective role,
and its other possible functions in sperm attraction.
``
70
Bio-Engineering
Structural Modeling of DNA Loops in Lac-Repressor
S. Goyal and N. C. Perkins
sgoyal@umich.edu and ncp@umich.edu
Experimental studies of DNA have established that its long-length scale structural
mechanics play a crucial role in its biological functions including gene expression. For
instance, long-length scale supercoiling regulates the unwinding of the smaller-length
scale helical coils of its constituent strands (the two sugar-phosphate chains) that enclose
the genetic information (the base pairs). Many proteins interact with DNA to deform it
into loops (and supercoils) as crucial steps in initiating or repressing gene expression.
The goal of our research is to model DNA as a nonlinear elastic rod under bending and
torsion to explain its long-length scale looping behavior. Loop formation in elastic rods is
often initiated by instabilities under compression and/ or torsion and accompanies
nonlinear transitions to more energetically favorable equilibria. These large nonlinear
deformations are governed by various structural properties of the rod including its
bending and torsional stiffnesses, anisotropy and stress-free curvature. Furthermore, these
properties are known to vary along the length of DNA because they depend on the basepair sequence. The dynamics of a DNA strand is also influenced by its physical
interactions with the surrounding fluid medium. For example, the fluid exerts
hydrodynamic and thermal forces on DNA, and its ionic composition screens electrostatic
repulsion of the negatively charged phosphate backbone of DNA.
Our dynamic rod model yields a set of nonlinear partial differential equations in time and
and space (along the rod’s contour length). These equations need to be solved
numerically under known initial and boundary conditions. We employ this computational
rod model to simulate various examples of DNA supercoiling, one of which is will be
presented herein.
The activity of a lactose (sugar) producing gene in the bacterium E.coli is structurally
controlled by a “Lac-repressor” protein. The repressor protein binds to two sites (operator
regions) on this gene to mechanically deform it into a loop. The crystal structure of this
DNA protein complex unfortunately cannot reveal the loop geometry, but it does provide
clues about the boundary conditions for the loop. We use our computational rod model of
DNA with these boundary conditions to predict the possible loop geometries. Many
ongoing experiments on the Lac-repressor protein are exploring the sequence-dependent
behavior of looping by working with the various man-made mutants of the gene. To
complement these experiments, we will explore through simulation the sensitivity of the
loop shape to sequence dependent stiffness, stress-free curvature, and chirality.
``
71
Biomechanics
Homozygosity for a Dominant Mutation in col1a1 Restores Bone
Phenotype in Comparison to Moderately Severe Type IV
Osteogenesis Imperfecta Present in Heterozygous Brtl Mice
K.M. Kozloff, C. Bergwitz, T.E. Uveges, T. Chen, M.D. Morris, G.
Gronowicz, F. Ledgard, J.C. Marini, S.A. Goldstein
kenkoz@umich.edu
Keywords: Bone mechanics, osteogenesis imperfecta, genetic mutation
The Brtl mouse is a dominant-negative model for type IV osteogenesis imperfecta (OI).
Brtl is heterozygous for a glycine substitution (G349C) in one col1a1 allele. Brtl pups
have 30% perinatal lethality; surviving Brtl mice have reduced BFR and MAR and
smaller, weaker, and more brittle bones than WT. Unexpectedly, mice homozygous for
the G349C mutation are not lethal but have viability and size indistinguishable from WT.
Only mutant 1(I) mRNA is detected and virtually all 1(I) chains form homodimers.
This study characterizes the 1st mouse in which homozygosity for a dominant mutation
(Brtl/Brtl) attenuates the phenotype of the heterozygous mouse.
Femurs from 2 month Brtl, Brtl/Brtl, and WT mice were assessed for areal BMD by
PIXImus, geometry and vBMD by µCT, load to failure in 4-pt bending, and
histomorphometry. Tibial sections were imaged by Raman spectroscopy to measure
collagen cross linking. Areal and vBMD are normal in the Brtl/Brtl. Femoral cross
sectional area is intermediate between Brtl and WT. While Brtl femurs fail earlier in
bending than WT, Brtl/Brtl femurs appear normal. Furthermore, Brtl/Brtl femurs do not
demonstrate the reduced post-yield displacement characteristic of the Brtl mouse.
Ultrastructural parameters suggest Brtl/Brtl appears to rescue hypermineralization and
abnormal collagen cross linking in the Brtl matrix. On static histomorphometry, Brtl/Brtl
TbN is equal to WT, and significantly higher than in Brtl. TbTh of Brtl/Brtl is
intermediate between Brtl and WT, as is BV/TV. Percent ObS and OcS, MAR and
BFR/BS were the same in all genotypes. Dermal fibril diameter was significantly larger
in Brtl/Brtl than Brtl or WT. In Brtl, approximately 25% of 1(I) chains are linked as a
homodimer by S-S bonds between mutant Cys 349 residues. The homodimers form
efficiently in collagen heterotrimers and are well-secreted from the cells. Collagen triple
helices containing a single mutant chain comprise 50% of the intracellular collagen of
Brtl; these helices are not well secreted (30-50%) from cells but do occur in media and
matrix.
The moderately severe bone phenotype in Brtl may result from a combination of collagen
matrix insufficiency and the dominant negative effect of the reactive cysteine moiety.
Surprisingly, bone composed entirely of type I collagen containing an S-S dimer appears
to be sufficient for supporting normal functional requirements.
``
72
Biomechanics
Thrombospondin-3 Effects on Bone Structure and Function
J.A. Meganck, S. Hormuzdi, P.B. Bornstein,
S.A. Goldstein, K.D. Hankenson
meganckj@umich.edu
Keywords: Bone mechanics, Matrix proteins, genetic mutation
Thrombospondin-3 (TSP3) is a pentameric extracellular matrix protein present in bone
tissue. It is homologous to the well characterized cartilage oligomeric matrix protein
(COMP, also known as TSP5), however, the role of TSP3 in the skeleton has not been
previously examined. Therefore, the goal of this study was to determine the effect of
TSP3 on bone structure and function.
Mice with a targeted disruption of the TSP3 gene were created to examine its functional
significance. The mice were viable and fertile, and embryos developed normally. To
examine the effect of TSP3 disruption on post-natal bone modeling, femurs were
obtained from male and female TSP3-null and wild-type (WT) mice at 9, 15, and 26
weeks of age. Body weight was measured before harvesting. To determine if an absence
of TSP3 protein affected bone geometry, femora were scanned using a micro-computed
tomography (CT) system. Bone length, the moment of inertia, cortical thickness,
endosteal and periosteal radii and cross-sectional area were calculated on the resulting
CT images. Hematoxylin and eosin, Von Kossa and Toludine Blue stains were used to
assess histological differences. Four-point bending was used to investigate differences in
mechanical properties by measuring the stiffness, yield load, ultimate load, failure load,
yield displacement, ultimate displacement, failure displacement, pre-yield energy, postyield energy and total energy. In addition, these mechanical test results were used in
conjunction with the CT results to calculate the predicted yield stress and predicted
Young’s modulus. Results were considered to be significant if p<0.05 using the MannWhitney U test.
Female 9-w TSP3-null mice showed an increase in weight, the moment of inertia,
endosteal and periosteal radii, cross-sectional area, yield load, ultimate load, failure load,
and a decrease in modulus. Similarly, 15-w TSP3-null females had increased moment of
inertia, periosteal radius, cross-sectional area, stiffness, ultimate load, failure load, and
post-yield and total energy. Higher values for weight, moment of inertia, endosteal and
periosteal radii, stiffness, ultimate load and failure load were also seen in 9-w TSP3-null
male mice. When evaluating CT scans, we noted that the femoral head in TSP3-null
seemed to develop earlier than in wild-type mice. In TSP3-null mice growth seemed to be
completed by 15-w, whereas in WT mice growth had not begun until 26-w. Histological
analysis showed that the WT femoral head was composed of hypertrophy chondrocytes in
a calcified matrix until 26-w, while TSP3-null femoral heads showed vascular invasion
and ossification beginning at 9-w. Overall, these results show that adolescent male and
female TSP3-null mice have greater femoral bone volume and strength and accelerated
endochondral ossification of the femoral head.
``
73
Biomaterials
Keto-reactive coatings for patterning of biomolecules
Himabindu Nandivada and Joerg Lahann
nhima@umich.edu, lahann@umich.edu
Keywords: microcontact printing, surface engineering
Patterned polymer films are used as scaffolds for tissue engineering, components in
molecular electronic and optical devices, biosensors and in fundamental studies of cell
biology. These thin-film coatings provide free reactive functional groups, presenting an
attractive option for surface engineering.
Chemical vapor deposition (CVD) polymerization has been used to prepare
functionalized coatings, for patterning of proteins. The immobilization chemistries for
this type of patterning typically involve amide formation. The intrinsic chemical
reactivity of the functional groups promotes reaction with biological ligands and can be
used for pattern formation using microcontact printing (µCP). However, there is a need
for alternative reactive coatings that are compatible with immobilization chemistries
other than amide formation.
In this study, an approach towards the creation of
engineered microenvironments based on coatings
with a new reactive polymer coating, poly(p-xylylene
pentafluoroethyl ketone) (PPX-CO-C2F5), is reported.
The
precursor
for
CVD
polymerization,
pentafluoroethyl ketone [2.2]paracyclophane, was
synthesized via Friedel-Crafts acylation between
pentafluoropropanoic
anhydride
and
Fig 1: Fluorescence image of
[2.2]paracyclophane in the presence of AlCl3. The
TRITC-labeled streptavidin
polymer was then synthesized utilizing CVD
conjugated to biotin-based
polymerization. These reactive polymer coatings
ligands, which were patterned
present keto groups on their surfaces, which can be
onto the reactive coating using
then covalently bound to biological ligands with
µCP.
hydrazide groups. To prove this concept, we used µCP by covalently binding biotinbased ligands to the surface and then using rhodamine-labeled streptavidin to detect
them. As shown in Fig. 1, the binding between biotin and streptavidin facilitates the
creation of patterns of streptavidin on the polymer surface. The use of streptavidin as a
bio-linker generates a platform for further attachment of various biotin-conjugated
biomolecules such as proteins, antibodies, polynucleotides or polysaccharides.
This research demonstrates a substrate-independent technique for reactive coatings
consisting of vapor deposition of a keto-reactive coating and µCP, which can be used for
the creation of spatially designed microenvironments. These surfaces can effectively
support self-assembly of proteins, antibodies and mammalian cells and thus can be
applied in various fields, such as microfluidics and drug delivery.
``
74
Biomaterials
Spatial Control of Protein within
Biomimetically Nucleated Mineral
L. N. Luong, R. J. Patel, and D. H. Kohn
lluong@umich.edu
Keywords: biomimetic, coprecipitation, mineralization, and protein
Coprecipitation is a method used to incorporate protein into an osteoconductive bone-like
mineral layer onto an organic substrate, which can lead to an effective growth factor
delivery system. A bone-like mineral layer nucleated onto an organic substrate enhances
osteoconductivity and mechanical properties 1. Incorporation of protein may also render
the mineral osteoinductive. In this study, coprecipitation was used to incorporate bovine
serum albumin (BSA) into mineral nucleated onto polylactic-co-glycolic acid (PLGA)
films in order to control protein localization. Incorporation was characterized by
determining its presence on the film, the quantity incorporated, and its localization.
Films were prepared using 5% wt. PLGA/chloroform solution cast in 10 cm Petri dishes.
After air drying, films were cut into 4 cm2 squares and etched in 0.5M NaOH for 7
minutes per side. A modified simulated body fluid (mSBF) was used in order to induce
mineralization 2. The following groups were examined: (1) 3 days in mSBF, 3 days
adsorption, (2) 3 days in mSBF, 3 days coprecipitation, (3) 3 days in mSBF, 2 days
adsorption, 1 day in mSBF, (4) 3 days in mSBF, 2 days coprecipitation, 1 day in mSBF
and a control group mineralized in mSBF for 6 days. Films were incubated in 40 ml of
mSBF with 200 μg/ml of BSA at 37ºC and mSBF was changed daily. For the adsorption
samples, 0.25 ml of 200 μg/ml of BSA in PBS was pipetted onto each film. Fourier
transform infrared spectroscopy (FTIR) was used to determine the presence of BSA
within the mineral layer. BSA quantification was done using a bicinchoninic acid assay
and absorbance was measured at 562 nm. Samples were demineralized in 0.01M HCl and
agitated at 300 rpm for 3 days. BSA localization was determined by coprecipitating
fluorescently-labeled BSA (5:1 ratio of BSA to labeled-BSA) onto the films and
examining the films with a confocal microscope.
FTIR confirmed the presence of BSA in the mineral. Coprecipitation increased the
quantity of BSA in the mineral in addition to controlling the localization of BSA through
the mineral. This suggests that BSA is incorporated into the mineral as opposed to
weakly adsorbing to the surface. Permutations of growth factors can therefore be
incorporated into the bone-like mineral layer and/or the actual polymer by controlling the
number of days a growth factor is being coprecipitated. By being able to control the
loading and localization of the protein through the mineral thickness, an effective release
profile can be achieved.
1.
2.
``
Murphy WL: J Biomed Mater Res 2000; 50(1):50
Murphy WL: J Am Chem Soc 2002; 124:1910
75
Solid Mechanics and Materials
Ultrasonic Transmission Characteristics of
Continuous Casting Slab for Medium Carbon Steel
Jun Youn Lee and Professor Soon-Bok Lee
leewnsdus@kaist.ac.kr
Keywords: ultrasonic, longitudinal wave, Rayleigh wave, continuous casting slab,
attenuation coefficient
Until now, works to remove surface defects of continuous casting slab have been
achieved by forced surface scarfing in order to guarantee intermediate-materials for
producing high quality steel materials in industry. In addition, investigations detecting
internal defects inside slab have been progressed to improve the quality of continuous
casting slab. Now a new effective evaluation technique on surface and internal defects of
slab is required for increasing actual incoming rate of slab and acquiring defect-map. It
has been reported that the attenuation of ultrasonic wave is very severe in casting
structures because of many voids, grain boundaries of coarse grains, surface defects and
so on. However, considering the poor surface state and high temperature of continuous
casting slab, non-destructive evaluation technique based on stress waves whose
transmission is comparatively excellent has to be adopted. Accordingly, this research was
performed for getting basic transmission characteristics of ultrasonic wave on continuous
casting slab as a preliminary step of advanced ultrasonic defect testing.
Ultrasonic wave is classified mainly to three kinds of type, such as longitudinal wave,
transverse wave and Rayleigh wave. These three kinds of ultrasonic were applied to carry
out experiments to investigate ultrasonic transmission characteristics of continuous
casting slab in this research. First, transmission testing of transverse wave was not easy
because its initial input energy was not sufficient to travel through thick continuous
casting steel and the degree of its attenuation was as well too severe in casting structure.
Next, longitudinal wave testing was performed in the frequency range of 0.5MHz to
25MHz and basic data set included attenuation coefficients, its frequency characteristics
and so on was acquired. Finally, transmission testing of Rayleigh wave was carried out in
the frequency range of 1MHz to 5MHz. From this measurement testing, the basic data set
of attenuation coefficients could have been obtained. And Rayleigh waves were also
applied on several types and levels of surface defects. The types of surface defect to have
been applied in measurement testing are vertical line defects, horizontal line defects,
circular defects and closed defects. When Rayleigh wave propagating along the path
meets a defect, the energy loss occurs by reflection and dispersion of wave. Consequently
the degree of loss on each type of defects was measured by Rayleigh wave testing.
``
76
Material
Effects of Impact Velocity on Crush Strength of Aluminum
Honeycombs
Sung-tae Hong and Jwo Pan
sthong@engin.umich.edu
Keywords: Aluminum honeycombs, Dynamic crush behavior, Inclined loads
Effects of impact velocity on the crush strength of aluminum 5052-H38 honeycomb
specimens are investigated by experiments. An impact test machine using pressurized
nitrogen was designed to perform dynamic crush tests. A test fixture was designed such
that inclined loads can be applied to honeycomb specimens in dynamic crush tests. The
results of dynamic crush tests indicate that the effects of impact velocity on the normal
and inclined crush strengths are significant. The trends of the inclined crush strengths for
specimens with different in-plane orientation angles as functions of impact velocity are
very similar to that of the normal crush strength. Experimental results show similar
progressive folding mechanisms for honeycomb specimens under pure compressive and
inclined loads. Under inclined loads, the inclined stacking patterns were observed. The
inclined stacking patterns are due to the asymmetric locations of horizontal plastic hinge
lines. These experimental observations provide a better understanding of the dynamic
crush behaviors of aluminum honeycombs under pure compressive and inclined loading
conditions.
u
u
v
One fold
H
H+D
H
One fold
H-D
Plastic hinges
(a)
Plastic hinges
(b)
Figure 2 Simple two-dimensional schematics of the stacking patterns: (a) under pure compressive
loads and (b) under compression dominant inclined loads.
``
77
Solid Mechanics and Materials
High Speed Tensile Test for the Material Properties
at the Intermediate Strain Rate
Ji-Ho Lim, Seok-Bong Kim, and Professor Hoon Huh
ksb79@kaist.ac.kr
Keywords: Intermediate Strain Rate, Dynamic Material Properties, Load Ringing
Phenomenon
The dynamic behavior of a material must be examined to ensure the impact
characteristics of an auto-body in finite element analysis. An appropriate experimental
method needs yet to be developed to acquire the material properties at the intermediate
strain rate ranged from 1/sec to 500/sec. In this study, tensile tests of various different
steel sheets for an auto-body were performed to obtain the dynamic material properties
with respect to the strain rate which is ranged from 0.003/sec to 200/sec.
For tensile test at intermediate strain rate, a high speed material testing machine
(HSMTM) of servo-hydraulic type was developed. This apparatus has the maximum
velocity of 10 m/sec to obtain the dynamic material properties at the strain rate of up to
500/sec. And a special jig fixture of a load cell was designed to reduce the trembling of
the load signal. This load-ringing phenomenon is induced by unstable stress propagation
along the specimen at the high strain rate.
In case of high speed tensile test, there is no special regulation about shape and size of the
specimens. Therefore it is necessary to decide adequate type of specimen for tensile test
at intermediate strain rates. In this study, dynamic tensile specimens were decided by
finite element analysis considering several shape factors, length(L), width(W) of gauge
part and radius(R) of fillet part. The shape L=20mm, W=6mm, R=6mm(L20W6R6) were
used at range of 0.1~100/sec and L15W6R6 were used at 200/sec strain rate.
From the dynamic tensile test, stress-strain curves were obtained for steel sheet SPCC,
SGACD, SPRC35R and SPRC40R with the variable strain rates. And the sensitivity of
yield stress for each steel sheet was observed according to the strain rates. The fracture
elongation for each sheel sheet is decreased at the strain rate of static to 0.1~0.5/sec, then
it is increased to 10~20/sec and decreased again at more high strain rates, like an `S`
shape. These stress-strain curves, relationship of the yield stress and the elongation to the
strain rate are significant not only in the crashworthiness evaluation under car crash but
also in the high speed metal forming.
``
78
Solid Mechanics and Materials
Determining material properties of thin films on substrates
Kristen L. Mills and Professor Michael Thouless
klmills@engin.umich.edu
Keywords: thin films
Thin films are often used on components of micro-devices as dielectric coatings and for
thermal or diffusion protection. They also occur incidentally on a material in an
environment that provokes a surface reaction. Manufacturing technology and processing
advances have allowed thin films to be cast, deposited, or grown in layers as thin as a few
nanometers. The challenge that this poses for the materials engineer is determining the
material properties at these very small length scales. In most cases, direct measurement
of the material properties of the film is impossible.
Plasma oxidized Polydimethysiloxane (PDMS) will be used to illustrate a methodology
for determining the material properties of a film, in this case the plasma-treated layer, for
which neither the thickness of the layer nor any of its material properties are known a
priori. This thin film is currently providing a platform on which cell biologists are
studying the adhesion, migration, and proliferation of cells. PDMS sheet is fabricated
and then plasma oxidized to create a very thin oxide layer on the surface of the PDMS.
Subsequently, nano-cracks are produced in this layer in the direction perpendicular to an
applied strain. The cracks provide a bio-mimetic and reconfigurable pattern in which
proteins are placed for the adhesion of cells.
Controlling the crack patterns necessitates an understanding of the mechanics of nanocracking. This, in turn, requires knowing the modulus, toughness, thickness, residual
strain of this layer and, perhaps, cohesive strength of the layer. The behaviors of the film
that may be used to deduce information about it will be discussed as will measurement
methods that are required at the scale of hundreds of nanometers to analyze them.
``
79
Soild mechanics and Material
Study on interfacial delamination of thin film/substrate structure
by push-off test
Woo Sung Choi and Youn Young Earmme
woosung@kaist.ac.kr
Keywords: bridged thin film, delamination, nanoindenter
In recent years, thin films and coatings have been increasingly used in various
applications, including bio-electronic systems, micro/nano electronic devices, MEMS or
NEMS , etc. In order to design and fabricate these devices, it is essential to measure the
mechanical properties and interfacial toughness of thin films. The mechanical properties
are closely related to device performance and reliability. However, it is difficult to
measure the mechanical properties of thin films because of its small feature size. Several
techniques have been applied to the mechanical characterization of thin films, such as
nanoindentation, micro/nano tensile test, membrane deflection test, and so on. Interfacial
delamination is related to lifespan, and structural integrity of thin film adhesion, it was
not until the introduction of a fracture mechanics approach that interfacial adhesion
strength was studied extensively and systematically. Many adhesion test techniques have
been developed to measure the adhesion energy of interface, such as blister test, peel test,
pull-off test, etc.
In this study, the push-off experiment of bridged gold thin film on silicon substrate using
nanoindenter was carried out to measure the mechanical properties of gold film and the
critical energy release rate as the interfacial delamination criterion between the gold film
and silicon substrate. Analytical constitutive relations are derived here based on
membrane theory and are compared with experimental results. The critical energy release
rate was evaluated based on the general concepts of interfacial fracture mechanics. In
order to compare analytical result with experimental one, two-dimensional geometricallynonlinear FEA (finite element analysis) is also carried out to simulate the push-off
experiment, and the energy release rate is calculated.
FORC
E
``
80
Tissue Regeneration and Cellular Biotechnology
Micro-device for manipulating and shaping cells in tissue
engineering
Konstantinos Varsos and Jonathan Luntz
kvarsos@umich.edu
Keywords: Cell manipulation, Tissue engineering, Programmable force fields
In many biological applications the manipulation of bio-material is very useful. The
desired task is to be able to handle bio-particles to bring them to a desired position and
orientation. Particle manipulation includes basic functions like particle detection,
sampling, analysis, separation, isolation and conveyance. These functions can effectively
be used in biological systems in several applications like biochemical reactions, sample
analysis and synthesis, molecular genetics, biotechnology production, development and
testing, clinical diagnostics, cell manipulation, lab-on-chip, etc. This research focuses on
manipulation of cells by creation of force fields using the electrical phenomenon of
dielectrophoresis (DEP) for the application of bioengineering of muscle tissue. For this
purpose we have constructed a linear array of electrodes which based on the distributed
manipulation theory, can bring cells to a certain position with certain orientation. We
provide an analysis of the manipulating device.
``
81
Bioelectrics
An algorithm for design of power systems for single and multicomponent devices: a case study focusing on a MEMS
environmental test monitor
Kimberly Cook and Dr. Ann Marie Sastry
amsastry@umich.edu
Keywords: power supply, battery, MEMS, gas chromatography
Fine manipulation of the smallest of analytes using microscale devices for biological
assay, separation and catalysis implicitly requires reconsideration of power supply. Power
sources typically exceed the mass and volume of all other subsystems of a MEMS device,
and thus commensurate reduction in the sizes of power supplies is required to maintain
device portability. This is particularly critical in applications wherein the sampling device
is designed to be small and easily deployed, such as the University of Michigan WIMSERC environmental monitoring device. This testbed comprises a small sensor capable of
detecting dozens of environmental contaminants within a few minutes, using a microscale
gas chromatograph sampling a very small volume of ambient air. Our objective is to
design an optimal hybrid power supply for this device.Our algorithm allows design of
both single and multi-component power systems. Three methods of optimization have
been developed for generic MEMS devices: 1) specification of single-source power
supply based on aggregate power profiles, 2) determination of optimal (minimum mass
and/or volume) hybrid power systems, based on ranges of power required, and 3)
identification of optimal hybrid power supplies based on constrained locations within the
system.
A stepwise outline of the algorithm follows:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
``
User supplies power targets and environmental constraints.
Environmental requirements are used to eliminate electrochemistries.
Subdevice performance parameters are computed.
Approaches 1, 2, and 3 are applied to subdevice parameters.
Energy, voltage, and current ratios (maximum/available from cell) are computed.
Conditionality statements are applied.
Power configurations are eliminated based on mass, volume, or area target values.
Batteries are selected based on specific or energy properties for Approaches 1 and
2, and based on packaging constraints for Approach 3.
Batteries are selected based on maximum lifetime.
Results from all three approaches are compared and the system is selected, based
on initial user criteria, or if multiple strategies are feasible, by longest lifetime.
82
Bioelectrics
Nano-tubular structured conducting polymers for neural
prostheses applications
Mohammad Reza Abidian, Professor David Martin
mabidian@umich.edu
Keywords: Nanofibers, electrospinning, Nano-tubes,
electrochemical polymerization, neural prostheses
Conducting
polymers,
Neural prosthetic devices, and specifically microelectrode arrays, facilitate the functional
stimulating or recording of neurons of the Central Nervous System (CNS) and Peripheral
Nervous System (PNS). The interface between microfabricated neural microelectrodes
and neural tissue plays a significant role in the long term performance of these devices. It
is thought that biocompatible polymer coatings can stabilize the interface between
microelectrode and living tissue at the site of implantation. The ability of neural
electrodes to record high signals over extended periods of time remains the significant
problems. The engineering of bioactive electrode coatings has been investigated for its
potential to promote in-growth of neural tissue, reduce shear stress, and enhance signal
transport from electrons to ions at the electrode-host interface.
We have found that films of electrospun nanofibers can be deposited on the surface of
these devices, followed by electrochemical polymerization of conducting polymers such
as polypyrrole or poly(3,4-ethylenedioxythiophene) in the presence of counterions. After
polymerization, nanofibers templates can be dissolved, leaving tiny channels, pores and
nano tubular structures in the conducting polymers. This morphology facilitates efficient
signal transport and communication with the neural tissue.
The electrical properties of the polymer functionalized probes were examined with
impedance spectroscopy and cyclic voltametry. The impedance spectroscopy revealed
that the impedance of gold electrode significantly decreased from 800 kΩ to 8 kΩ. The
surface morphology of the coated electrodes was assessed by optical microscopy and
scanning electron microscopy. Scanning electron microscopy showed the nano tubular
structure of conducting polymers on the electrode sites.
``
83
Bioimaging
Quantitative Contrast Analysis of In Vivo Ultrasound Imaging: A
Study With a Combined 3D Ultrasound/Digital Mammography
System
Rebecca C. Booi, Gerald L. LeCarpentier, Marilyn A. Roubidoux, Ajay
Kapur, Ramon Q. Erkamp, and Paul L. Carson
rbooi@umich.edu
Keywords: medical imaging, breast, sonography
A combined 3D ultrasound/digital mammography system is being developed to better
detect and/or characterize breast lesions. It was hypothesized that quantitative
measurements of image quality would reveal only modest differences in lesion image
quality between direct contact hand held scanning and automated scanning through a
mammographically-compatible compression paddle using this system.
Automated 3D ultrasound/digital mammography (AUS/DX) studies and direct contact,
hand held scans were performed on 10 women with simple cysts. The whole breast, AUS
was performed through a mammographic plate 1.0mm or 2.5mm thick, with a GE Logiq
9 M12L transducer array at 10 MHz. Gain was adjusted higher than usual so the upper
1/3 of the cyst showed measurable signal.Signal in the cyst to within 1 mm from the wall
was compared with that from adjacent fat and glandular tissue. Log decompressed
signal was averaged over five slices in the ROI.
In automated (and hand) scans, signal levels were: cyst -67.7 (-68.7) dB; fat -51.7 (-52.1)
dB; and glandular -45.2 (-43.5) dB. This indicates contrast in automated (hand) US scans
were 14.1±9.7 (16.1±8.7) dB between fat tissue and cyst, and 25.2±20.6 (26.8±22.5) dB
between cyst and glandular tissue. Mean depths of the centers of the cysts in the two scan
modes were 18.5±1.78 (17.6±2.95) mm.
With the automated system, relative contrast loss in vivo is apparently from increased
reverberation and multiple scattering signal in the essentially echo free cysts and signal
attenuation in the plate and in the greater depth of the cysts from the transducer. These
contrast losses are approximately consistent with the signal loss (~4 dB) and increased
reverberation levels (~1 dB) measured when imaging line targets through the
compression paddles. Half the signal loss through the paddles can be compensated with
no increased ultrasound exposure levels to the patient by increasing the transmitted
power. The small contrast loss is consistent with radiologist impressions that the image
quality was modestly reduced compared with expert scanning. The differences may well
be worth the advantages of whole breast AUS and can be reduced by employing a
transducer of lower frequency.
``
84
Bioimaging
Entropic Graphs for Simultaneous Multi-image Registration and
Atlas Construction
Huzefa Neemuchwala, Alfred Hero, Paul Carson and Charles Meyer
hneemuch@umich.edu
Keywords: entropic graph, atlas, registration, nearest neighbor, mutual information
In many applications, fusion of two or more images acquired via sensors requires image
alignment to an identical pose, a process called image registration. Image registration
methods select a sequence of transformations to maximize an image similarity measure.
Recently, we introduced a new class of entropic-graph similarity measures for image
registration [1]. We extended image registration to higher dimensional feature spaces
using Renyi's generalized alpha-entropy. The alpha-entropy is estimated directly through
continuous quasi additive power weighted graphs such as the minimal spanning tree and
k-Nearest Neighbor graph. Estimates of Renyi-mutual information are derived for multidimensional feature distributions using entropic graphs.
A significant application of this technology is that it allows us to generate atlas images
for image databases. Anatomic atlas images are widely used for registration, automatic
segmentation, gene mapping and image retrieval. Image registration can be accomplished
by mutual information minimization for an entire set of images that contribute to a
multidimensional feature probability density function. Histogram methods for density
estimation are largely unsuccessful in constructing atlases due to the exponential growth
of computer memory required to build higher dimensional histograms. The use of graph
methods allow us to form atlas images for image databases with significant
computational ease as opposed to histogram methods. A second application is the
registration of multiple images aimed at tracking disease and possibly tumors through
registration of several time-sampled images of patients simultaneously.
The higher dimensional feature sets used in this work include wavelets and image
moments. We propose initially to generate image atlases for the Yale face database [2],
but intend to extend our work to 3D medical images of the brain, imaged using magnetic
resonance imaging. Multi-image registration will be demonstrated over ultrasound
images of the breast from a patient undergoing chemotherapy for breast cancer treatment.
1.Neemuchwala HF and Hero AO, “Entropic graphs for registration”, to appear in Multisensor image fusion and its applications, Eds. R. S. Blum and Z. Liu, Marcel-Dekker,
Inc 2004.
2.Georghiades AS, Belhumeur PN and Kriegman DJ, “From Few to Many: Illumination
Cone Models for Face Recognition under variable lighting and pose”, IEEE PAMI,
vol. 23(6), pp 643-660, 2001
``
85
Bioimaging
Effects of acquisition parameters and reconstruction methods
on the correction of motion and susceptibility artifacts in fMRI
K. K. Pandey, B. P. Sutton, Lauren Maddox, D. C. Noll
kpandey@umich.edu
Signal loss due to intravoxel dephasing and off-resonance image distortions are two
major manifestations of magnetic susceptibility artifacts in functional MRI. Head motion
changes the orientation of tissue interfaces relative to B0 and thus, the appearance of these
distortions in raw T2*- weighted images. Incorporation of methods that abate image
distortions and intra-voxel dephasing significantly reduced the error between the
reference image and movement corrected image. In this study, we examine the effect of
acquisition parameters and reconstruction methods on motion correction in fMRI while
the imaged phantom is continuously moving across the time series of images.
Data was acquired using a spherical, layered susceptibility performing motion routine
with maximum angular displacement of ~8 degrees. Images were acquired using a GRE
spiral pulse sequence (TE 27 ms, FOV=24 mm), single-shot spiral-in/spiral-out
acquisition and reconstructed using a conjugate phase image reconstruction. Spiralin/spiral-out images were reconstructed using an iterative method using dynamically
updated fieldmaps. Images were motion corrected using FSL, and the realigned images
were subtracted form the reference image. The error calculated was compared across the
various acquisition parameters and reconstruction methods to determine which
parameters and reconstruction methods would lead to the most accurate and complete
motion corrected images.
On average, the spiral-in /spiral-out images reconstructed with the iterative reconstruction
method using dynamically updated field-map were most accurate, followed by the spiralin, spiral-in/spiral-out images, and the spiral-out images being the least accurate. A
comparison of the pre and post motion corrected images also revealed that motion
correction was most effective in the images reconstructed with the iterative method (33%
error reduction) compared to CP spiral-out (28%) and CP spiral-in/out & spiral-in
(~25%) respectively.
We found that the use of acquisition parameters that are less sensitive to off-resonance
and susceptibility artifacts, along with the incorporation of dynamic estimates of
susceptibility-induced inhomogeneities in presence of motion during imaging, results in
better motion corrected images. Acquisition methods that are more robust to
susceptibility artifacts, namely, spiral-in and spiral in-out acquisitions produced more
accurate motion corrected images. As expected, the iterative method using the dynamic
field-map estimates resulted in more complete motion correction since these field-maps
were able to account for motion induced dynamic changes in the local field
inhomogeneity and off resonance effects due to motion.
``
86
Bioimaging
Optical and ultrasonic monitoring of laser-generated intracellular
contrast agents: initial cell culture studies
M.J. Zohdy,C. Tse, J.Y. Ye, L. Balogh, T. Norris, M. O’Donnell
Acoustically monitored laser-induced optical breakdown (LIOB) can be used as an important
diagnostic and therapeutic tool in living cells. With properly controlled laser parameters, optical
breakdown is a minimally invasive means to target a single, transient, acoustically detectable
contrast agent (microbubble) within a cell, without affecting its viability. With different laser
parameters, optical breakdown can effectively obliterate a target cell. Simultaneous real-time
acoustic and optical microscopy can monitor this range of effects.
In this study, experiments were performed on a monolayer of CHO-K1 (Chinese hamster ovary)
cells cultured on a glass coverslip. To initiate and monitor intracellular photodisruption in real
time, we have developed a system integrating an ultrafast laser with optical and acoustic
microscopy. A regeneratively amplified Ti:Sapphire laser produced the breakdown, and a highfrequency (50 MHz) ultrasonic transducer, confocal with the laser, monitored the resultant
bubble via continuous pulse-echo recordings. The photodisruption was also observed using
optical microscopy, and the viability of each target cell was assessed after laser exposure using
conventional live/dead staining.
By varying laser pulse fluence (from a minimum of 7 J/cm2 to 112 J/cm2) as well as the number
of applied pulses, a broad range of intracellular effects was studied. When up to 5000 laser
pulses were applied at the minimum fluence, a small (1μm), transient bubble was generated.
Target cells in this regime retained viability several hours after laser exposure. In contrast, with
even a few laser pulses at high fluence, a large (>6μm) stable bubble was formed, and target cells
were consistently killed in this regime.
Geometric targeting within cells can thus generate acoustically detectable microbubbles without
introducing exogenous agents. Furthermore, by incorporating biochemical targeting agents, this
system can also be used as a powerful tool for molecular diagnostics (e.g. detecting targeted
molecular agents without affecting cell viability) and therapy (e.g. by destroying targeted cells
without damaging cells in the vicinity).
``
87
Dynamics, Systems and Controls
DETERMINING MODEL ACCURACY AS A FUNCTION OF INPUTS
AND SYSTEM PARAMETERS
Bryon Sohns, Prof. Jeffrey L. Stein
bsohns@umich.edu
Keywords: Model Accuracy, Model Validation
Vital to the effectiveness of simulation-based design is having a system model of known
quality. Previous research introduced an algorithm called AVASIM for assessing model
validity systematically and quantitatively. AVASIM assess the accuracy and validity of a
model based on a specific input and set of system parameters. The purpose of this
presentation is to present a AVASIM-based methodology that defines a range of validity
of a model with respect to input and system parameter variations
Two illustrative examples are presented to explore the feasibility of the proposed
procedure. The first example analyzes a linearized version of a nonlinear transient
vehicle-handling model. This model’s accuracy and validity are evaluated with respect to
variation of two system parameters, resulting in a two-dimensional range of validity.
Then a complex nonlinear hydrogen fuel cell model is linearized in order to investigate
its accuracy and validity with respect to two input parameters. This again results in a
two-dimensional range of validity, but with respect to input rather than system
parameters.
The results agree well with what is expected for the various models based on knowledge
of the effects of linearization on model accuracy. The proposed algorithm for assessing
model range of validity is a promising tool for determining model quality and thus
potentially useful for simulation-based design.
``
88
Dynamics, Systems and Controls
Using Neural Network Surrogate Models to Optimize the Valve
Timings for a 2.4 Litter VVT Engine
Bin Wu, Zoran Filipi and Dennis Assanis
bwuz@engin.umich.edu
Keywords: spark-ignition engine, variable valve timing, optimization, neural network
In the past thirty years, various Variable Value Timing (VVT) technologies were
developed to improve fuel economy, to increase torque generation, and to reduce
pollutant emissions. All those new technologies provide more flexibility in controlling
the breathing behavior of the engine. Accompanied with the extra flexibility, there are
more independent actuators that require proper controls. In conventional Spark-Ignition
(SI) engines, the two primary independent actuators are the fuel injector and the spark for
each cylinder. Independent camphasing doubles the number by introducing the intake and
exhaust camphasers. Consequently, we have to define the desired camshaft positions for
each engine operating point, i.e. the combination of engine speed and load.
In this study, the optimization of camshaft positions is investigated. The optimization
objective varies with respect to the engine’s operating mode. At full load, the
optimization objective is maximizing the torque generation, and the camshaft positions
are regarded as functions of engine speed only. Under part load conditions, the
optimization objective is reducing the fuel consumption while satisfying torque
command. The optimized camshaft positions are regarded as functions of both engine
speed and load.
In this study, we propose using Artificial Neural Networks (ANN) as surrogate models
for torque generation and brake specific fuel consumption (bsfc) of the 2.4 liter VVT
engine. The ANNs learn the desired relationship from training samples. The training
samples are collected on a dynamometer test facility for representative combinations of
intake and exhaust camshaft positions, engine speed, and intake manifold pressure.
Systematic structure sweeps are conducted to find out the best network structure for each
ANN model. Then, the optimization is conducted on the ANN surrogate models for
selected operating points. Finally, the optimized results are organized as lookup tables
that can be implemented into the Engine Control Unit (ECU).
The proposed algorithm can be potentially extended to include more degrees of freedom,
such as valve lifts and durations, that will emerge with more general Variable Vale
Actuation (VVA) technologies.
``
89
Dynamics, Systems and Controls
CT-free Cup Orientator Using Sensors In THR
Byunghoon Ko, Sukhoon Park, and Yongsan Yoon
bhko@kaist.ac.kr
Keywords: Image guided surgery, CT-free, Total hip replacement
The purpose of this research is to propose CT-free cup orientator using tilt sensors
without expensive point tracking devices in total hip replacement. In the case of using a
mechanical guide, the accuracy of cup orientation can be sacrificed because of change of
the patient’s posture during procedure. Several navigation systems have been introduced
to secure an accurate position and orientation of the implant in THR. These systems are
expensive and have some weakness due to possible interference in optical measurement.
Our orientator employs a T-bar shaped gauge and economic tilt sensors to secure a fairly
accurate orientation of acetabular cup in THR.
A Study on the Design of an Acoustic Actuator Based on the
Singing Mechanism of Cicadas
Wan-Ho Cho and Professor Jeong-Guon Ih
elen@kaist.ac.kr
Keywords: Cicadas, Acoustic actuator
This study was motivated by the fact that the cicadas sound is very loud and broad-band
whereas its body size is quite small. These facts suggest that the singing mechanism of
cicadas can offer a good idea in the design of an acoustic actuator. The main parts of
cicadas singing organ are comprised of abdomen cavity and tymbal. This study is
interested in tymbal system. Tymbal action was modeled as a nonlinear motion of a
curved shell. The results revealed that such an analogous system to the cicadas singing
organ can suggest a design concept for a new acoustic actuator.
``
90
Design and Manufacturing
Modular Logic Control for Reconfigurable Manufacturing
Systems
Emanuel Almeida and Dawn Tilbury
{almeidae, tilbury}@umich.edu
Keywords: Logic Control, Reconfigurable Manufacturing, Finite State Machines
Contemporary manufacturing systems are incredibly complex, consisting of hundreds of
machines working together in a coordinated fashion to produce parts. The complexity of
the machines leads to complexity in their control systems, and complexity is expensive.
The controls for a new machining system can often consume half of the systems
construction time and cost. A more effective way to program these types of
manufacturing controllers could lead to significant economic savings. The Modular
Finite State Machine (MFSM) framework is a new way of designing and programming
control logic. This framework allows complicated control problems to be broken down
into manageable blocks for design purposes. A module can be dedicated to a single
mechanical module, or to a single logical function. A designer can then focus on the logic
of that module, its interaction with the adjacent modules, and a small portion of the
physical system.
This framework has been used at U of M to control several test beds and manufacturing
systems. The latest implementation has been the design of the System Level Controller
(SLC)
for
the
Reconfigurable
Factory
Test
Bed
(http://eclipse.engin.umich.edu/RFTindex.html) at the Engineering Research Center.
MFSMs are used to provide the SLC with the necessary “intelligence” to control and
manage a whole manufacturing system, including both hardware and software
components. The hardware components include a Serial Parallel Machining Line (with
several CNC machines and robots inside manufacturing cells joined by a conveyor) and
an AGV. The software components include a Virtual Factory Manufacturing Cell and
Assembly Cell, a Diagnostic Database and HMI Interfaces. This system has a distributed
control architecture where most communication is done using OPC, an open standards
protocol for communication, making it an extremely modular, scalable and
reconfigurable manufacturing control system.
``
91
Design and Manufacturing
Closed-Loop Tape Springs as Fully Compliant Mechanisms Preliminary Investigations
Christine Vehar, Dr. Sridhar Kota, and Dr. Robert Dennis
cvehar@umich.edu, kota@umich.edu, bobden@umich.edu
Keywords: compliant mechanism, tape spring mechanism, closed-loop tape springs,
compliant joints, bi-stable mechanism
The paper introduces tape springs as elements of fully compliant mechanisms. The
localized folds of tape springs serve as compact revolute joints, with a very small radius
and large range of motion, and the unfolded straight segments serve as links. By
exploiting a tape spring’s ability to function as both links and joints, we present a new
method of realizing fully compliant mechanisms with further simplification in their
construction. Tape springs, typically found in carpenter tape rules, are thin-walled strips
having constant thickness, zero longitudinal curvature, and a constant transverse
curvature. The paper presents a closed-loop tape spring mechanism. By representing its
folds as idealized revolute joints and its variable length links as sliding joints connecting
rigid links, we present a modified Gruebler’s equation to determine its kinematic and idle
degrees of freedom. To realize practical utility of tape spring mechanisms, we propose a
simple actuation scheme incorporating shape memory alloy (SMA) wire actuators and
successfully demonstrate its performance with a proof-of-concept prototype. The paper
also presents potential applications for actuated tape spring mechanisms including a large
displacement translational mechanism, planar positioning mechanisms, bi-stable, multistable, and variable stiffness mechanisms.
``
92
Design and Manufacturing
MACHINING OF ELASTOMERS
Jie Luo and Albert Shih
jluo@umich.edu
Keywords: Elastomer machining, Cryogenically cooling, Chip formation, Induction
heating
Novel methods, elastomer machining using sharp, woodworking tools, the machining of
cryogenically cooled elastomers, and the machining with an induction-heated tool, to
enable the effective machining of elastomers are presented. Use of some down-cut endmilling tools effectively removed the elastomer material at room temperature and
generated a clean groove. Cooling the elastomer workpiece by solid carbon dioxide
improved the machined surface finish. Optical pictures and SEM micrographs were used
to examine and classify chips. The induction heating is applied to raise the temperature
of an end milling tool for machining of elastomers. Experiments are conducted to study
the effect of tool rotation and model the heat transfer between the tool and thermal
insulator. Some end milling tests with induction heated tool were performed and results
showed that the use of heated tool improves the surface appearance of the milled cuts.
Development of 3D position tracking System using
PSD(Position Sensitive Detector) sensors for surgery
Hyunjun Shin, Yougsan Yoon
bhlee@novic.kaist.ac.kr
Keywords: 3D position measurement, PSD sensor, tracking system, active marker
Currently, most of the 3D position measurement devices for surgery use image sensors.
They have resolution order practically and they use markers. However, most 2D image
sensors (CCD or CMOS) need massive calculation to find marker center. In this research,
we are going to use PSD sensor. PSD sensors are suited for position detector sensor in
that their output give the coordinate of marker center directly.
In this research, we are going to explain how to measure the accurate position of marker.
And we are developing this system with primary target of total hip replacement surgery.
``
93
Design and Manufacturing
Characterization of Friction Drilling Process: Force, Torque,
Temperature, and Material Analysis
Scott Miller and Professor Albert Shih
scotfran@umich.edu
Friction drilling is a nontraditional drilling method developed to penetrate a hole and
create a bushing in a single step. The relevant concept of this technique is heat
generation from frictional force between a conical tool and a sheet metal workpiece,
which softens and allows displacement of workpiece material into a bushing shape.
However, details of this concept are not fully understood. This research studied aspects
of friction drilling including measurements of force, torque, and temperature during the
process. A model of force and torque was developed and compared to experimental
results.
Optical Methods for Reconfigurable Precision Measurement
Zhenhua Huang and Professor Albert Shih, Jun Ni
zhenhuah@umich.edu
Keywords: Optical measurement
This research studies non-contact optical stereovision and laser holography methods for
precision reconfigurable measurement of automotive powertrain components and porous
foam materials. This study is motivated by the situation in industry that fast, accurate,
and full surface sampling optical methods for online powertrain component measurement
are on high demand. In this study, the accuracy and gage repeatability and
reproducibility (R&R) of the two systems for precision measurement are evaluated. The
effect of the commonly-used powder spray on the accuracy and gage R&R of specular
surface measurement is quantified. An algorithm is proposed for plane feature extraction
of porous foam materials.
``
94
Design and Manufacturing
COMPLIANT PART ASSEMBLY MODELING AND DIMENSIONAL
VARIATION DIAGNOSIS USING DESIGNATED COMPONENT
ANALYSIS
Chino Imediegwu
Products made of compliant sheet metals are widely used in the automotive, aerospace,
and electronics industries. One of the paramount challenges for the assembly process of
such compliant parts is the assembly dimensional variation which affect end product
functionality, reliability and perceived quality. This is particularly true for compliant,
non-rigid parts because clamping and joining operations during assembly may introduce
more dimensional variation as a result of deformation and springback phenomena. To this
effect, various methods for analyzing or diagnosing sources of dimensional variation
have been developed with the aim of enabling quick detection and localization of
assembly process faults based on inline dimensional measurements. Furthermore, in
seeking to improve engineering product designs and reduce the number of problems that
occur during the assembly of a new product due to dimensional variation, manufacturing
firms have focused more on integrating downstream product development processes in
earlier design stages. This has been made possible by practices such as concurrent
engineering, partnership sourcing, design for manufacturability, process driven product
design and modular design.
The integration of resources and methodologies have typically been effected on the front
end of product development in scenarios characterized by complex products with
complicated assembly processes such as the automotive industry. In such situations,
manufacturing firms have employed sequential validation techniques to approve
components, then subassemblies and finally the end product. This sequential process
validation approach is typically characterized by increased costs due to rework and
lengthened lead times. This study seeks to improve designated component analysis as an
analytical tool and then use it to evaluate, quantify and correct dimensional variation in
compliant sheet metal assembly particularly for non orthogonal designated patterns. This
tool can then be utilized to ensure a significant reduction in product validation time, cost
and tool rework through out the assembly process.
``
95
Design and Manufacturing
Vehicle Crashworthiness Design via Equivalent Mechanisms
and Crash Mode Matching
Karim Hamza and Professor Kazuhiro Saitou
khamza@engin.umich.edu
This research is motivated by the difficulty that faces vehicle designers when tackling the
task of crashworthiness design. Vehicle structure behavior during crash is often
unpredictable and requires enormous computational resources to simulate. Approximate
models are introduced, which draw upon the analogy between the collapse of the vehicle
structural members and the motion of space mechanisms. The equivalent mechanism
models offer physically sound approximations, which retain the gross behavior or crash
modes of real vehicle structures. Preliminary results show success in providing insightful
guidance to improving sub-optimal designs at a vastly reduced computational effort
compared to direct optimization approaches.
Design of heat-reversible snap fits for space frame bodies
Mohammed Shalaby and Dr. Kazuhiro Saitou
mshalaby@umich.edu
Recent legislative efforts to reduce the environmental impacts of the life cycle of
manufactured products have increased the need for component reuse and recycling.
Although aluminum space-frame is a good solution, its recycling is still a problem. Snapfit is a preferred joining method because: no need of separate fasteners, easily assembled,
can be disassembleable, reduces overall product cost and makes the recycling process
more economic, and provides clean separation between frame and panel. This research
proposes heat actuated reversible snap-fits, for vehicle frame/panel assembly. Optimum
location of these snaps, meeting certain NVH requirements, is found using genetic
algorithms and ABAQUS.
``
96
Design and Manufacturing
A Transport Model Approach for Developing
Microfiltration Compatible Metalworking Fluids
Fu Zhao, Andres Clarens, and Steven Skerlos
fzhao@umich.edu, aclarens@umich.edu, skerlos@umich.edu
Keywords: Metalworking fluids, microfiltration, design for environment
As a recycling process, microfiltration of semi-synthetic metalworking fluids (MWFs)
has been shown to increase the longevity and quality of MWFs, and reduce the
environmental and occupational health risks associated with MWF applications.
Research is currently being performed to better understand the transport of MWFs
through microfiltration membranes, including mechanisms of membrane fouling. A
mechanistic model was developed to describe the flux decline during microfiltration, and
to correlate experimentally observed flux with transport retardation mechanisms.
Parameters involved in MWF design such as oil content, surfactant to oil ratio, and
surfactant structure were investigated, and guidelines for formulating microfiltration
compatible MWFs were developed.
Preference Coordination in Engineering Design Decision-Making
Jeremy Michalek, Fred Feinberg, and Panos Papalambros
michalek@umich.edu
Design optimization methodologies offer assistance to engineers in achieving product
performance objectives; however, in practice most design problems involve tradeoffs
among a set of competing objectives such as performance, cost, and marketability. It
remains an open question: “How can a designer best navigate these tradeoffs to select the
most preferred design, particularly when social and economic preferences conflict with
user preferences and the user population itself is diverse?”
Preference coordination draws upon the rich literatures in marketing, economics, and
psychology to model preference structures of individuals and groups and coordinate these
preferences with design models of engineering performance. The rigorous coordination
of these models assists the designer in making tradeoff decisions by providing usable
information about consumer preferences for product characteristics and price, economic
preferences of the producer, and societal preferences such as reduced environmental
impact. Use of preference coordination is demonstrated to improve profitability
substantially relative to disjoint decision-making. When coupled with models of
heterogeneous consumer preferences, manufacturing systems, and public policy models,
it can be used to design product lines and to study the effects of regulation policy on
design decisions for navigating the tradeoff between private and public preferences.
``
97
Design and Manufacturing
Design for product-embedded disassembly
Shingo Takeuchi and Professor Kazuhiro Saitou
stakeuch@umich.edu
With growing interest in recovering materials and subassemblies within consumer
products at the end of their lives, there has been an increasing interest in Life-cycle
design that generally determines their desirable disassembly sequences in which ecointensive, eco-valuable components (subassemblies) are efficiently retrieved. The
objective of this study is to determine near optimal configurations of a product with
product-embedded joints when a disassembly sequence is given by Life-cycle
assessment. Since the search space is quite large even for relatively simple products,
genetic algorithm (GA) is utilized to rapidly approximate optimal solutions.
``
98
Fluid Mechanics, Heat Transfer and Combustion
Numerical Simulation of Combustion Driven Oscillations
in Gas Turbine
Hyoun Jun, Kim and Professor Shin
kris@kaist.ac.kr
This study is motivated by the need to reduce combustion noise of gas turbine systems. In
order to understand cause of the combustion noise, computational method is introduced.
Its purpose is to explore qualitatively fundamentals by calculating another models .This
study will show the preliminary results through the verification of numerical code and
then investigation of the pressure fluctuation behavior on the dump combustor. Our
ultimate goal is to understand and develop control strategies for combustion noise by
expecting effects of pressure oscillation.
Flow and heat transfer analysis for the performance
improvement of Cross-flow fin-tube heat exchangers
Cheensu An and Professor Dohyung Choi
ancheensu@kaist.ac.kr
The flow and the heat transfer about the cross-flow fin-tube heat exchanger in an outdoor unit of a heat pump system has been numerically investigated. Using the general
purpose analysis code, FLUENT, the Navier-Stokes equations and the energy equation
are solved for the three dimensional computation domain. The flow solution provides the
effective permeability and the inertial resistance factor of the heat exchanger if the
exchanger were to be approximated by the porous medium. This information is essential
in carrying out the global flow field and temperature-field calculation of the heat
exchanger unit.
``
99
Fluid Mechanics, Heat Transfer and Combustion
Cycle-Resolved Charge Evolution Measurements In A Direct
Injected Engine Using Double-Pulse LIF
James Smith and Professor Volker Sick
smithdj@umich.edu
Keywords: Direct-Injected Spark-Ignition; Laser-Induced Fluorescence; Combustion
Stability; Stratified Charge
Advanced engine concepts such as the Direct-Injected Spark-Ignition (DISI) engine rely
on highly accurate spatial and temporal placement of fuel to achieve robust ignition and
subsequent combustion. This study utilizes double-pulse Laser-Induced Fluorescence
(LIF) to investigate fuel equivalence ratios on a cycle resolved basis inside a firing DISI
engine operating in the stratified charge regime. By imaging not only 2-D equivalence
ratio fields, but also the evolution of these fields over time, more can be learned of the
causes of engine misfire so that preventative measures can be taken.
Electrokinetic Pumps for Dynamic Actuation of Cochlear
Implants during Surgical Insertion
Meng-Ping Chang, Robert J. Bartz, and Professor Hasselbrink
mpchang@umich.edu
Keywords: electroosmosis, electrokinetic pump, cochlear implants, shape control
A key difficulty in using cochlear implants during surgical insertion is that the implants
can only reach a certain depth because of imperfect shape match of cochlear and
implants. A Bourdon-tube-like design allows for real time hydraulic actuation of the
shape of the implants during insertion, but this requires fast-response high pressure/low
flow rate integrated micropumps. We are building and characterizing electrokinetic
micropumps for hydraulic actuation in this and similar applications. The electrokinetic
pump can be built in a variety configuration: such as porous glass frit or nano-channels
on a glass substrate. Results show pressures of 7 psi/volt and successful actuation of the
cochlear implant backing device using the glass frit pump; characterization of the
micropump and challenges for long-term operation of micropumps will also be
addressed.
``
100
Fluid Mechanics, Heat Transfer and Combustion
Modeling of Porous Filter Permeability via Image-Based
Stochastic Reconstruction
Fu Zhao and Professor Steven J. Skerlos
fzhao@umich.edu
The current design of porous filtration system widely used in pollution prevention
applications relies heavily on empirical models with parameters calibrated based on time
consuming experiments. This research develops a methodology for producing a porescale, 3D computational model of porous filter permeability that is based only on the
analysis of 2D images of the filter matrix (e.g., acquired from photography or electron
microscopy) and first principles. The computationally reconstructed porous filter model
retains statistical details of porosity and its spatial correlations within the filter, and can
be used to calculate permeability for either isotropic or 1D anisotropic porous filters. It is
shown that the model can predict water flux directly from first principles with deviations
from experimental measurements on the order of experimental error, and the
methodology yields predictions of permeability that are similar or better than predictions
offered by existing filtration models, while not requiring experimentally determined
coefficients.
Temperature-Dependent Luminescence Quenching in Random
Nano Porous Media
Xiulin Ruan and Professor Massoud Kaviany
xruan@umich.edu
The luminescence quenching of a random, crystalline one-dimensional model porous
medium doped with rare-earth elements, is analyzed by considering the transport,
transition, and interaction of the fundamental energy carriers. The quenching in nano
porous media is enhanced compared to a single crystal, due to multiple scattering,
enhanced absorption, and low thermal conductivity. The coherent wave treatment is used
to calculate the photon absorption, in order to allow for field interference and
enhancement. The luminescent and thermal emission is considered as incoherent. The
luminescence quenching and nonlinear thermal emission, occurring with increasing
irradiation intensity, are predicted.
``
101
Fluid Mechanics, Heat Transfer and Combustion
A Fully Integrated CFD and Multi-zone Model with Detailed
Chemical Kinetics for the Simulation of HCCI Engines
Aristotelis Babajimopoulos and Professor Dennis Assanis
ababajim@umich.edu
Keywords: HCCI, CFD, Combustion, Chemical Kinetics, Mixing
Temperature gradients present in an engine cylinder due to heat transfer to the cylinder
walls and composition stratification due to insufficient mixing can have a significant
effect on the combustion process in a Homogeneous Charge Compression Ignition
(HCCI) engine. Modeling this process is a challenging task, because both mixing and
chemistry must be handled in a computationally efficient way. A modeling approach that
fully integrates a CFD code (KIVA-3V) with a multi-zone model with detailed chemical
kinetics is introduced. At each computational timestep, a multi-zone model provides the
KIVA-3V with the necessary energy source terms for each cell, by solving the detailed
chemical kinetics for groups of cells (zones) with similar properties.
An Experimental Investigation of the Effect of Fuel
Concentration on Nonpremixed Jet Flames
Tershia Pinder and Arvind Atreya
tpinder@engin.umich.edu
Keywords: nonpremixed flames, composition oscillations, transient combustion
Appropriate mixing of fuel and air is important for efficient combustion and for reducing
pollutant formation during combustion.
While unsteady techniques have been
experimentally examined, most of these studies correspond to flow field fluctuations and
not composition fluctuations. In this work, the effect of inlet fuel concentration
fluctuations on a nonpremixed jet flame are examined to obtained a better understanding
of the mixing and pollutant formation processes. The effects of oscillation frequency and
Reynolds number on radiation and species emissions are studied using spectrally and
spatially resolved infrared images and temporally and spectrally resolved line-of-sight
emission and absorption measurements.
``
102
Fluid Mechanics, Heat Transfer and Combustion
Effect of Increase in CO2 Concentration on Radiative Properties
of Unsteady Spherical Diffusion Flames in Microgravity
Melissa Chernovsky and Professor Arvind Atreya
mchernov@umich.edu
The objective of this research is to experimentally and theoretically investigate the
contribution of CO2 as a diluent in the reaction zone of a gaseous diffusion flame in
microgravity. Tests are conducted with ethylene, C2H4, diluted with CO2 and control
mixtures of non-reacting diluents. Time-dependent measurements of the flame radius,
flame temperature, spectral radiation, and the spatial distribution of soot are obtained.
Numerical analysis examines the interaction between flame radiation and chemistry.
Experimental work is conducted at the 2.2 second drop tower at the NASA Glenn
Research Center. The aim of this research is to improve our fundamental understanding
of combustion processes and help develop fire suppression and detection technology for
space applications.
Transient Spray Cone Angles in Pressure-swirl Injector Sprays
Jordan A. Snyder, Ronald O. Grover, Jr., Professor Volker Sick and
Professor Dennis Assanis
janyder@engin.umich.edu, rgrover@engin.umich.edu
Keywords: sprays, pressure-swirl, nozzle fluctuations
The transient cone angle of pressure swirl sprays from injectors intended for use in
gasoline direct injection engines was measured from 2D Mie scattering images. A variety
of injectors with varying nominal cone angle and flow rate were investigated. The general
cone angle behavior was found to correlate well qualitatively with the measured fuel line
pressure and was affected by the different injector specifications. Experimentally
measured modulations in cone angle and injection pressure were forced on a
comprehensive spray simulation to understand the sensitivity of pulsating injector
boundary conditions on general spray structure. Ignoring the nozzle fluctuations led to a
computed spray shape that inadequately replicated the experimental images; hence,
demonstrating the importance of quantifying the injector boundary conditions when
characterizing a spray using high-fidelity simulation tools.
``
103
Biomechanics
Dynamic Modeling of Karate Front Kick
Jiro Doke and Professor Arthur D. Kuo
jdokeh@umich.edu
Keywords: karate kick, biomechanics, dynamic modeling
A front kick is one of the most common forms of kick in karate. From observation, the
hip and the knee of the kicking leg go through a sequence of flexion and extension phase.
However, it is not well known how this coordination of joints relates to the performance
of the kick, and whether this is the optimal sequence. A computer simulation model was
created to examine the effect of coordination and joint torque activation levels on foot
speed at impact. The results showed that the hip is the primary driver for the kick, and
the knee contributes more during extension rather than during the initial flexion phase.
``
104
Bio-engineering
Optimized Design of a Thoracic Artificial Lung Using
Computational Fluid Dynamics
Jeongho Kim, MS; Keith Cook, PhD
jeonghok@umich.edu
Computational fluid dynamics (CFD) was applied to the design of the inlet and outlet of a
thoracic artificial lung (TAL). Numerical calculations were performed in a threedimensional geometry. A porous media model was used for the fiber bundle inside the
TAL. As an inlet boundary condition, steady, uniform inlet flows (Q) were given between
zero to 20 L/min. The outlet boundary was pressure equals zero mmHg. Inlet and outlet
diameters of 1/2", 5/8", and 3/4" were used to find a relationship between device pressure
drop and inlet/outlet diameter. Results indicate that pressure drop (ΔP) increases
quadratically with flow rate; ΔP = 0.42001 Q2 + 0.2134 Q (R2 = 0.99), ΔP = 0.13388 Q2
+ 0.22859 Q (R2 = 0.99), and ΔP = 0.05618 Q2 + 0.14044 Q (R2 = 0.99) for 1/2", 5/8",
and 3/4" inlets, respectively. Increasing diameter, furthermore, markedly reduces pressure
drop. At 4 L/min of flow, pressure drop was 8.06 mmHg, 3.82 mmHg, and 2.23 mmHg
for 1/2", 5/8", and 3/4" inlets.
Human balancing strategy used by riding bicycle as slow as
possible
Hogene Kim, Professor James Ashton-Miller
hogenek@umich.edu
Keywords: Inertial measurement unit, Accelerometer, Angular rate gyro, Loss of control
Identifying human control strategy on balancing a bicycle is highly nonlinear control
problem. This study will show different human control strategies in initial and adapted
period of riding a bicycle. Inertial measurement unit (IMU), which consists of three
perpendicular accelerometers and angular rate gyros, was successfully developed and its
signals from human upper body and bike, during riding a bicycle as slow as possible,
identified different movement characteristics between initial and adapted period. The
future study will continue to investigate human control strategy on balancing a bicycle
and possible reasons for loss of control.
``
105
Bioengineering- Biomechanics
Enhanced Mineralization and Reduced Toughness in the Aging
Brtl Mouse Model for Type IV OI
K.M. Kozloff, T.E. Uveges, J.C. Marini, S.A. Goldstein
kenkoz@umich.edu
Keywords: Bone mechanics, osteogenesis imperfecta, genetic mutation
Osteogenesis imperfecta (OI) is a connective tissue disorder resulting from mutations in
type I collagen. While generally thought of in terms of its pediatric implications, lifespan
in patients with normal cardiopulmonary status may be normal. Consequentially,
maintenance of bone health later in life is critical to the long-term care of the OI patient.
The Brtl mouse model for type IV OI provides a means to investigate long-term effects of
a G349C point mutation in one col1a1 allele on whole bone structure-function
relationships. This study characterizes the skeletal phenotype of the Brtl mouse at an
advanced age of 18 months.
``
106
Solid Mechanics and Materials
Analysis of polymer deformation in nanoimprint lithography
by using molecular dynamics simulation
Ji-Hoon Kang and Professor Kyung-Woong Kim
deli@kaist.ac.kr
Keywords: Molecular dynamics simulation, nanoimprint lithography, adhesion, polymer
deformation
In this study, molecular dynamics simulations of nanoimprint lithography in which a
stamp with patterns is pressed onto amorphous poly-(methylmethacrylate) (PMMA)
surface are performed to study the deformation of polymer. Force fields including bond,
angle, torsion, inversion, van der Waals and electrostatic potential are used to describe the
intermolecular and intramolecular force of PMMA molecules and stamp.
As the simulation results, the mechanism of polymer deformation is investigated by
means of inspecting trajectory of particles and molecular configurational properties. The
adhesion forces between stamp and polymer are calculated and its effects on the polymer
deformation are also studied. Consequently, the simulation results will give us
understanding of polymer deformation in nanoimprint lithography and will be utilized for
the design of nanoimprint lithography.
A study on interfacial delamination in thin film structure
by pull test
Woosung Choi and Professor Y.Y Earmme
woosung@kaist.ac.kr
Keywords: bridge thin film, delamination, nanoindenter
In recent years, thin films and coatings have been increasingly used in many widely
various applications. Although a thorough understanding of mechanical properties and
interfacial delamination is desired to ensure the reliability of thin-film adhesion, it was
not until the introduction of a fracture mechanics approach that interfacial adhesion was
studied extensively and systematically. In this study, the bridge delamination experiment
was used to test the mechanical response of freestanding thin film gold specimens with
nanoindenter. Analytical constitutive relations are derived here based on membrane
theory and are compared with experimental results. In order to compare analytical and
experimental result, a two-dimensional geometrically nonlinear FEA is also carried out to
simulate the pull-off test, and the energy release rate is obtained.
``
107
Bioengineering
A 3D Dual Transducer Ultrasound Technique for the Assessment
of Vascular Flow using Contrast Agent Imaging
Nelson Chen and Drs. J. Brian Fowlkes, Paul Carson and Gerald
LeCarpentier
ngchen@umich.edu
We are developing a dual-transducer technique that enables rapid three-dimensional
vascular flow data collection in a tissue volume. Conventional refill imaging is extended
by separating the tasks of contrast clearance and readout, and assigning them to separate
ultrasound probes mounted on a computerized translation system. Refill data for the
entire volume at a given time point is gathered during each sweep. Multiple sweeps
complete the refill curves for the volume. Data is combined to provide a threedimensional vascular flow map. Initial results show strong correlation (r=0.96, p=0.005)
between data thus collected and data collected with traditional interval imaging.
Stochastic Simulation of Biometal binding to Protein Sensors
Munish V. Inamdar, Yun-Bo Yi, Christian Lastoskie, Carol Fierke, Ann
Marie Sastry
minamdar@umich.edu
Keywords: zinc, protein, biometal, transport, intracellular, carbonic anhydrase, diffusion,
stochastic simulation
Zinc performs crucial catalytic, structural and regulatory roles in the body, though its
tight regulation is essential, due to its potential toxicity in the cell. We use direct
stochastic modeling to study interactions between zinc ions and carbonic anhydrase (CA)
molecules, used as intracellular sensors for zinc. We have developed simulations of local
interactions of zinc ions and these high-affinity and selectivity CA sensors. The resulting
simulations are capable of extracting association rate, dissociation rate and dissociation
constants for CA-zinc reaction in water; this extends significantly the present capability
of the traditional diffusion approach in this field.
``
108
Bio-Engineering
The effects of low frequency ultrasound on droplets and bubbles
Andrea H. Lo, Oliver D. Kripfgans, Paul L. Carson, J. Brian Fowlkes
ahlo@umich.edu
Ultrasound (US) induced gas bubbles have the potential to be used as a tool for cancer
therapy. With the use of US, dodecafluoropentane (DDFP) droplets can be vaporized in
tissue and/or in the vasculature to create microbubbles at desired locations. Bubbles
driven by low frequency US, which is less susceptible to attenuation, can be useful as
they can either oscillate at their resonant frequency to create mechanical damage in the
surrounding area or scatter energy to increase local thermal effects. By using tissue
mimicking polyacrylamide gels, the effects of low frequency US on droplets and bubbles
are investigated.
Multi-image registration and image atlas construction using
entropic graph based mutual information estimation
Neemuchwala HF, Hero AO, Park HJ, Carson PL, Meyer CR.
hneemuch@umich.edu
Keywords: image registration, atlas, entropic graphs, mutual information
We present a new method for multi-image registration and atlas construction using
entropy methods. Multidimensional estimates of Renyi α-entropy and Renyi α-mutual
information are derived using entropic graphs such as nearest neighbor graphs. Thus, we
overcome the computational and statistical drawbacks of pixel histograms for
multidimensional entropy estimation. Further, we use wavelet feature vectors as opposed
to conventional scalar pixel features. Graph methods allow us to simultaneously register
or construct atlas images for large patients databases, a significant improvement over
current capabilities of histogram methods. A clustering approach is used to estimate
depth of images in the databases to provide an initial estimate of the atlas image.
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109
Tissue Regeneration and Cellular Biotechnology
ELECTROKINETIC PHENOMENA DURING ELECTROELUTION
FROM CLINICAL SAMPLING STRIPS
Sun Min Kim and E. F. Hasselbrink, Jr.
sunmk@umich.edu
Keywords: Electroelution, Macro-to-micro interface, Unsteady electrokinetics
In this research, a micro device for eluting protei
used for oral fluid sample collection was fabricated using PDMS (Poly dimethylsiloxane)
polymer. PDMS polymer has been used to fabricate micro systems due to easy and fast
fabrication, low cost, and compatibility with bio materials.
BSA (Bovine Serum Albumin) and OVA (Ovalbumin) were labelled with FITC
(Fluorescein isothiocyanate) dye for detecting movements using a fluorescent
microscope. About 50% of the initial concentration of BSA and OVA was eluted by the
~20V/cm electric field strength.
During the electroelution process, unsteady electrokinetic phenomena by the pressure
driven flow and the pH change of the reservoirs were observed.
This electroelution device can be integrated with a protein concentrator and a separation
column to analyze proteins. This integrated device will be fabricated in near future.
Inverted Colloidal Crystals as a Tissue Engineering Scaffold
Jungwoo Lee, Nicholas Kotov
jungwoo@umich.edu
Keywords: Inverted colloidal crystals, Scaffolds, Tissue engineering
An inverted colloidal crystal which has a well interconnected porous geometry provided
ideal structure for the tissue engineering scaffolds. Hydrogels are commonly used as a
biomaterial for scaffolds because of their biocompatible and biodegradable
characteristics. The aim of this study was to address the hypothesis that inverted colloidal
crystals consisted with hydrogels enhanced three dimensional cell-growth. Highly
ordered colloidal crystals with 100μm size polystyrene beads were prepared by the
modification of a conventional method. Poly (acryl-amid) hydrogels solution was used as
a scaffolding material. Good geometry of the scaffold improved mass transfer inside of
structure and promoted three dimensional formations of tissue.
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110
Bioengineering
Microfluidic Immunoassays using a Braille Display for
Computer-controlled Fluid Actuation
Yoko Kamotani, Wei Gu, Nobuyuki Futai, Shuichi Takayama
ykamotan@umich.edu
Keywords: Microfluidics, immunoassays, microfabrication
Microchannel immunoassays overcome the limitations of conventional assays with
enhanced reaction efficiency, simplified procedures, and reduced consumption of
reagents. We have developed a self-contained, automated microfluidic immunoassay
system. This system is fabricated with elastomeric poly(dimethylsiloxane) (PDMS) and
liquid flow is controlled using mechanical actuators provided by a commercially
available, refreshable Braille display. A combination of valves and independent pumps
actuated by an array of 160 Braille pins allow for simultaneous analysis of multiple
antigen samples. A fully automated immunoassay system will be beneficial to a variety
of fields including cellular biology and biochemical detection.
Endothelial Cell Culture Under Computer-controlled Flow in
Microfluidic Channels
Jonathan W. Song, Wei Gu, Nobuyaki Futai, Kristy A. Warner,
Jacques E. Nor, and Shuichi Takayama
songjon@umich.edu
Keywords: endothelial cells, microfabrication, cell culture, shear stress
We propose to study the effects of shear stress on endothelial cell (EC) alignment and
elongation within a microcirculatory mammalian cell culture system. For this purpose,
we have designed a microfluidic cell shearing chamber fabricated from
poly(dimethylsiloxane) (PDMS) that is computer-controlled through a refreshable Braille
display. The piezoelectric pins of the Braille display function as a network of
microfluidic pumps and valves that actuate fluid in a pulsatile nature. The system
demonstrates significant versatility in shear stress levels and rate of delivery that can be
recreated in evaluating the physiological and biological effects associated with shear
stress in ECs.
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111
Biotechnology, Muscle Mechanics
Effect of contraction-induced injury in young mice lacking
superoxide dismutase or glutathione peroxidase genes
Rainer Ng and Professor John A. Faulkner
nrn@umich.edu
Contraction-induced injury produces an initial mechanical disruption in the muscle
followed by a secondary injury several days later. Compared with untreated mice, mice
treated with a large molecular weight free radical scavenger show a 50% reduction in
force deficit. The decrease in the force deficit, along with the large mass of the scavenger,
are consistent with a secondary injury caused by ROS located in the extracellular matrix.
We tested the hypothesis that mice lacking intracellular antioxidants such as superoxide
dismutase and glutathione peroxidase will not respond differently from wild type mice to
contraction-induced injury. Comparison of force deficits and injured muscle fiber counts
on wild type and knockout mice will clarify the response to contraction-induced injury.
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112
Bio-Engineering
Nano-tubular structured conducting polymers for neural
prostheses applications
Mohammad Reza Abidian and Professor David C. Martin
mabidian@umich.edu
Keywords:
prostheses
Nanofibers,
electrospinning,
electrochemical
polymerization,
neural
The ability of neural electrodes to record high signals over extended periods of time
remains the significant problems. The engineering of bioactive electrode coatings has
been investigated for its potential to promote in-growth of neural tissue, reduce shear
stress, and enhance signal transport from electrons to ions at the electrode-host interface.
We have found that films of electrospun nanofibers can be deposited on the surface of
these devices, followed by electrochemical polymerization of conducting polymers such
as polypyrrole or poly(3,4-ethylenedioxythiophene) in the presence of counterions. After
polymerization, nanofibers templates can be dissolved, leaving tiny channels, pores and
nano tubular structures in the conducting polymers. This morphology facilitates efficient
signal transport and communication with the neural tissue.
The electrical properties of the polymer functionalized probes were examined with
impedance spectroscopy and cyclic voltametry. The impedance spectroscopy revealed
that the impedance of gold electrode significantly decreased from 800 kΩ to 8 kΩ. The
surface morphology of the coated electrodes was assessed by optical microscopy and
scanning electron microscopy. Scanning electron microscopy showed the nano tubular
structure of conducting polymers on the electrode sites.
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113
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