Bergamo Univeristy
Italy
June 12th-13th 2012
Lecture 3 – Use of CAE and ADAMS
Professor Mike Blundell
Phd, MSc, BSc (Hons), FIMechE, CEng
Improvements with MBS
INFORMATION
Concept
Design
Validate
Assembly
Service
With MBS
IMPROVEMENT
Product Development Process for Manufacturers
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Integrated CAE Technologies
CAD
FEA
CFD ?
MBS
Controls
Hydraulics
Testing
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Multibody Systems Analysis (MBS)
Virtual Prototyping (MBS) may be summarised as:
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The Analysis and Simulation of Mechanical Systems
Systems can consist of rigid and flexible bodies
Bodies are assembled using rigid joints or flexible connections
System elements such as springs and bushes can be nonlinear
The mechanism can move through large displacement motion
Automatic formation and solution of equations of motion
Animated and plotted presentation of results
Commercial Software available – ADAMS, SIMPACK, DADS, …
Typical Constraint Elements - Joints
Revolute
Spherical
Planar
Fixed
Cylindrical
Universal
Translational
Rack & Pinion
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Joint Library
Cylindrical Joint
Spherical Joint
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Joint Library
Planar Joint
Revolute Joint
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Joint Library
Translational Joint
Universal Joint
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Main Types of Analysis
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KINEMATIC - Movement controlled by joint selection and
motion inputs.Movements not effected by external forces or
mass properties.Systems have zero rigid body Degrees of
Freedom.
STATIC - Determine static equilibrium position and reaction
forces. Velocities and accelerations are set to zero. Often
needed before dynamic analysis (ie. full vehicle models). Can be
run QUASI-STATIC in time domain.
DYNAMIC - Complete nonlinear transient multi-degree of
freedom systems using numerical integration to solve the
equations of motion. Users can select the integrator for solution
and control the accuracy of the solution process.
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Graphical User Interface
Model Parameterisation
Occupant Protection Studies
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MADYMO Simulation of
Pedestrian Impact
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Pedestrian Human Body Model positioned:
- Walking posture
- Knee extended
- balanced in an upright position
No pedestrian initial velocity
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Vehicle initial velocity  39 km/h
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Bumper level  390 mm
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Bumper lead distance  200 mm
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Hood edge level  720 mm
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Adaptable Car Structures (ACS)
Bonnet in active position
Active-reversible bumper and bonnet concept (Pneumatic Muscle)
Typical Design Study
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Characteristic Curves
of Automotive Suspension
• Toe, Caster, Camber curves are
essential properties of a suspension
• Curves represent change in angular
orientation of wheel under different
loading conditions
• Curves must be continually evaluated
as design changes
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Simulation of Vertical Motion
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Typical Problem Statement
• Packaging problems with current design
• Tie-rod spindle connection point must be moved
• Would like to move tie rod:
– 10 mm outboard
– 14 mm aft
– 15 mm up
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A Past Approach
• Run two analyses: nominal
and design change
(considered)
• Compare the results
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Typical Report (old approach)
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Modern Methods
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Setup Design of Experiments
Analysis (DOE)
– Define design space
– Define trial runs
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Application of DOE
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Utilize parametric modeling tool
– Analyse set of trials picked by DOE theory
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Use DOE theory and the response surface method
– Fitted results give continuous information throughout design space
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Start with Design Space
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Add DOE Design Points
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Assign Trial Numbers
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Analyze Model at Each Trial
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Calculate Objective at Each Trial
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Map Trial Objectives back to
Design Space
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Create Response Surface
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Response Surface Method
• Provides continuous knowledge within design space!
• Can be extended (hard to visualize)
– More than 2 factors
– More complex objective types
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Contact Examples
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Forced Contact Step Output
• Animate using defined output steps
• Or animate additional contact frames
• Displays contacts between output steps
50 STEPS
152 STEPS
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ADAMS/Flex
• Integrating System-Level Motion Simulation and
Component-Level FEA
FE
Modes
ADAMS
Simulation
Stress
Distribution
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Flexible Satellite with
Automatic Controls
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Stabilizing the satellite’s orientation during deployment of flexible solar
panels
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Customization
Digital Functional Vehicle
Test Rigs
Chassis
Road
Full Vehicle
Engine
Driver
Driveline
Body
Suspension
Valvetrain
Transmission
Body-in-white
Steering
Cranktrain
Clutch
Frame
Brakes
Chain/Belt
Differential
Seating
Tires
Acc. Drives
Axles/CV
Restraints
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Total Vehicle Modelling
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Tutorial 4 - ADAMS
Demonstration Session
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Using ADAMS/Solver Files (Solver)
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Building Models interactively in ADAMS/VIEW
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Using an ADAMS/Command Files (AVIEW)
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Double Wishbone Example
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Prepare a System
Schematic
Calculate the model
Degrees of Freedom
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BODY/GROUND
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Plan the ADAMS/Solver
Input File
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Z
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X
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Y
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