New Graduate Student
Orientation
August 15, 2012
Dr. Phillip White
This presentation can be found at:
www.eng.utoledo.edu/~pwhite
Solid Mechanics Focus Group
•
Dr. Lesley Berhan
Assoc. Professor
Lesley.Berhan@utoledo.edu
NI 4025 419 530 8220
• Dr. Mohammad Elahinia Assoc. Professor Mohammad.Elahinia@utoledo.edu
NI 4045 419 520 8224
• Dr. Ali Fatemi
Professor
Ali.Fatemi@utoledo.edu
NI 4029 419 520 8213
• Dr. Yong Gan
Assist. Professor
Yong.Gan@utoledo.edu
NI 4024 419 520 6007
• Dr. Mohamed Samir Hefzy Professor
Mohamed.Hefzy@utoledo.edu
NI 1016 419 520 6086
• Dr. Ahalapitiya Jayatissa Assoc. Professor Aayati@utnet.utoledo.edu
NI 4049 419 520 8245
• Dr. Efstratios Nikolaidis
Professor
Efstratios.Nikolaidis@utoledo.edu
NI 4035 419 520 8216
• Dr. Mehdi Pourazady
Assoc. Professor
Mehdi.Pourazady@utoledo.edu
NI 4036 419 520 8221
• Dr. Phillip White *
Professor & Chair Phillip.White@utoledo.edu
Solid Mechanics
NI 4065 419 520 4241
Focus Group
* = not adding new students at this time.
Dr. Lesley Berhan
Research Interests:
• Negative Poisson’s ratio materials
• Nanocomposites
• Composites
• Heterogeneous materials
• Fibrous networks
• Structural mechanics
• Finite element analysis
Interested in hiring one or two graduate students
Modeling electrical percolation onset in polymer nanocomposites
Composite and Fibrous Materials Laboratory | University of Toledo
Dr. Lesley Berhan
Percolation in nanocomposites is of high interest because of the
potential to create electrically and/or thermally conductive systems
with an extremely low mass of particles. At relatively low
concentrations of nanofillers the electrical conductivity of polymer
nanocomposites dramatically increases.
The study of percolation is relevant to many areas of research including
thermal management, EMI shielding, and lightning strike protection
Conventional modeling approach
•Reinforcement (e.g. graphene platelets, nanotubes,
nanoparticles, etc.) modeled as fully penetrable objects
•Relationship between excluded volume and percolation
threshold used obtain percolation threshold
Hard-core modeling approach
•Reinforcement modeled as impenetrable objects (hard
core) embedded within a soft (i.e. penetrable) shell
•Excluded volume of objects found numerically
•Relationship between percolation threshold and
excluded volume found using Monte Carlo simulations
•Analytical solution will be derived and compared with
experimental results
Dr. Mohammad Elahinia
• I am looking for one Ph.D. student. The
area of the research is biomedical
applications of shape memory materials.
• Please see next slide.
Biomedical Applications of NiTi Shape Memory Alloys:
(I) Smart pedicle screw (II) Esophagus positioner
Majid Tabesh, Amin Mohaghegh, and Mohammad Elahinia
Dynamic and Smart Systems Laboratory, MIME Department, University of Toledo
Background
Shape Memory Alloys, such as equiatomic Nickel Titanium (NiTi or
Nitinol), undergo a phase transformation in their crystal structure when cooled
from the stronger, high temperature form (Austenite) to the weaker, low
temperature form (Martensite). This inherent phase transformation is the basis
for the unique properties of :
(I) Bio-inspired Shape Memory Alloy
Pedicle Screw to Compensate for
Bone Degradation in Osteoporosis Patients
(II) Bio-inspired Shape Memory Alloy
Esophagus Positioner
for Minimally Invasive Surgeries
Pedicle Screw: a particular type of bone screw designed for implantation
into vertebral pedicle.
Can be used in instrumentation procedures for fixating rods and plates to the
spine with the purpose of:
 Dynamic stabilization of the spine
 Immobilization for Spinal Fusion
 Spinal Deformity correction, …
Atrial fibrillation: an abnormal heart rhythm
(cardiac arrhythmia).
Involves the two upper chambers (atria) of the
heart.
Patients with AF are believed to have a
significantly higher risk of stroke
Radiofrequency ablation (RFA): catheter based treatment method
For patients who do not respond to other methods.
Low voltage alternating electricity at high frequencies to
create controlled thermal injury in a group of cells near the
pulmonary veins.
RFA could cause thermal injury to the esophagus (fistula).
The esophagus and posterior left atrium (LA) wall are in close contact over a
large area that may often lie within the atrial fibrillation ablation zone
The RF could burn the esophagus tissues, causing esophageal perforation
leading to mediastinal infection, stroke, and death.
Osteoporosis and spinal instrumentation
SMA esophagus positioner
Allows a material to return to its original
shape within a strain of up to 8% by
increasing the temperature.
Allows the formation of an elastic
behavior with significant recoverable
strain (up to10%)
NiTi is also biocompatible , biomechanically compatible, MR compatible, fatigue
resistant, etc which constitute excellent medical characteristics.
Self-expanding stents
Orthopedic staples
Osteoporosis is a systemic skeletal disease
characterized by low bone mass, micro architectural
deterioration of bone tissue, and a consequent increase
in bone fragility and susceptibility to fracture.
It is a major drawback in spinal instrumentation due
to hardware loosening or pulling-out both intra and
post operation.
SMA wires, if heated, will deflect the
esophagus away from the ablation site.
Anchoring system with expandable thread inserts
Conclusions
Shape memory alloy (SMA) technology offers new capacities to medical devices,
negotiating the obstacles in:
Spinal instrumentation of osteoporotic bone and
Initially, this SMA scaffold is
pre-compressed in its martensitic
state. As the scaffold is heated, due
to the body temperature, tends to
recover its original shape, to
maintain the inner diameter of a
blood vessel or any tubular passage.
Esophageal fistula during Radiofrequency ablation (RFA).
The SMA staple, in its opened
shape, is placed at the fractured
bone site. Through heating by an
external device, this staple tends to
close, compressing the separated
parts of bone to accelerate the
healing process of bone fractures.
References
1.
The screw assembly before placement
NiTi insert. Initial low-temperature (at
insertion). and closed high temperature form
(at withdrawal).
The screw assembly after placement
2.
Final form when reached to body temperature.
A portion of the insert from both ends
expands.
3.
H. Fischer, B. Vogel, and A. Welle. “Applications of shape memory alloys in medical instruments”. Minimally
invasive therapy and allied technologies, Volume 13, Issue 4 August 2004, pages 248-253.
H. A. Yuehuei. Internal fixation in osteoporotic bone. Edited by H. A. Yuehuei. Thieme Medical Publishers, INC.
2002.
D Sanchez-Quintana et al. Anatomic Relations between the Esophagus and Left Atrium and Relevance for
Ablation of Atrial Fibrillation. Circulation, v. 112 issue 10, 2005.
Dynamic and Smart Systems Laboratory
North Engineering Room 2045
Phone: (419) 530-8130
Fax: (419) 530-8126
http://smartsys.eng.utoledo.edu/
Fatigue and Fracture of Materials and
Structures
• Why an important area of research?
– Between 60% and 90% of all mechanical failures are
attributed to fatigue fractures (many textbooks on
fatigue)
– The cost of these fractures in the US alone is about
4% of the GNP (NIST study)
– Broad applications to many materials (metals,
polymers, composites) and to many structures and
industries (automotive, aerospace, power generation,
etc.)
– Several journals dedicated to this topic, including
International Journal of Fatigue, Journal of Fatigue
and Fracture of Materials and Structures,
Experimental Research
Laboratory
State-of-the-Art Facilities,
including:
•Servo-hydraulic Systems
– Three Axial Load Frames
– Torsion Load Frame
– Axial-Torsion Load Frame
•Electro-mechanical Systems
– Axial Load Frames (50 kN)
– Rotating Bending Machines
– Cantilever Non-rotating Bending
•Extensometry
– Mechanical Extensometers
– Video-Extensometer (Non-Contact)
•Crack Detection Systems
Related Graduate Level Courses
Regularly Offered
– Advanced Mechanics of Materials
– Fatigue of Materials and Structures
– Fracture Mechanics (offered this
term)
– Mechanics of Composite Materials
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Current Sponsored Research
Projects
Notched Fatigue Behavior under Constant and Variable
Amplitude Multiaxial Loading, Funded by US Navy Air
System Command
Development of a Axial Stress-Life Database for Gear
Steels in Aircraft Engine Applications, Funded by PrattWhitney
(A Division of United Technologies)
Fatigue Behavior and Modeling of Polymeric Materials,
Funded by General Motors
Axial and Bending Fatigue of Cast Iron including Stress
Concentration Effects, Funded by Eaton Corporation
Experiments and Modeling of Thermo-Mechanical Fatigue
of Polymeric Materials, Funded by General Motors
Strain-Controlled Fatigue Properties of 4037 Steel,
Funded by Chrysler LLC.
Strain-Controlled Deformation and Fatigue Behavior of
Sheet and Cast Aluminum for Structural Durability Design
and Evaluation, Funded by General Motors
Need More Information?
–Visit Dr. Fatemi’s Website
Dr. Yong Gan
• See next slides for research areas
• He is interested in working with Ph.D.
students and is seeking funding.
Outline
• Thermoelectric and Photoelectric Energy
Conversion
• High Temperature Thermoelectric Energy
Conversion Materials
• Synthesis of Photovoltaic
(PV)/Thermoelectric (TE) Nanofiber Arrays
• Preparation of Biophotofuel Cell Electrode
Thermoelectric property
Conductive and Oxidation
Resistant Silicates-Silver
Research Objective
To develop glass-based electrode materials
for high temperature thermoelectric energy
conversions that exhibit the following
properties: high conductivity, high oxidation
resistance and good bonding to TE legs.
Preparation of PV/TE Nanofiber Arrays
Biophotofuel Cell Design
Dr. Ahalapitiya Jayatissa
• Please see next slide
Nanotechnology and MEMS Laboratory, MIME Department
Current Research Projects:
1. Graphene based multiplexed Sensors: The main thrust of this research is to improve the
sensing properties of carbon nanotube and graphene based gas sensors by understanding
the mechanism underpinning the selectivity and sensing properties.
PhD: 1 student, MS: 1 student
2. Novel Material System based on Zinc-Oxy-Nitride: The determination of the properties
of the thin films so grown by a variety of experimental techniques, leading to a crosscorrelation between the growth parameters, the resulting film structure and its physical
properties.
PhD: 2 students
3. Laser Processing of Thin Films: The objective of this research project is to investigate the
fundamental phenomena of laser irradiation on metal oxide-based thin films relevant to gas
sensor performance by employing experimental as well as computational approaches.
PhD: 2 students
All projects involve Experimental activities and
Contact:
Professor A. H. Jayatissa
Tel: 419-530-8245
Room #: 4049 NI
E-mail: ajayati@utnet.utoledo.edu
Modeling/Simulations.
(Synthesis, coating and fabrication of thin
films, MEMS, and Sensors;
Modeling/Simulation based on finite element
analysis)
Dr. Efstratios Nikolaidis
• Research interest: Efficient Re-Analysis
Methodology for Sound and Vibration
of Large-Scale Structures
• Please see next slide
Definition and Significance
It is expensive to optimize vehicle body design by using
detailed FEM for sound and vibration
Vibratory displacement
and sound
Excitation
Uncertainty
Propagation
Monte Carlo Simulation
(10,000 replications)
Statistics of
displacement and
SPL
Design Optimization: Several MCS (e.g. 100)
Dr. Mehdi Pourazady
• Areas of interest: Applications of Finite
Element Methods in modeling and
numerical solution of problems in two
areas of Biomechanics and Nano
Engineering.
• He would like to have one MS and One
PhD student.