emea05-051
DESCRIPTION
gggTRANSCRIPT
-
Dynamic Front Wheel Curb Impact Study
Robert L. GeislerEngineering Group Manager Chassis CAE
General Motors - North American Product Development
Hyung-Joo Hong General Motors NAPD, Chassis CAEJason Kline General Motors NAPD, Chassis CAE
Prasad Kodali General Motors NAPD, Chassis CAE
-
Study History
1992 Robert Geisler & Prasad Kodali of CLCD invent a method to predict rear suspension curb impact loads and apply it to a vehicle program. Method included elastic-plastic representation of
the rear suspension toe link Correlation to test was very good
1995 Young Kim of LAD applies the above methodology to another suspension topology Correlation is also very good
-
Study History, cont.
1995 Robert Geisler of CLCD applies methodology to front curb impact simulation. These results did not correlate very well (analysis
loads are much higher than test loads). The theory is that a part of chassis was yielding
significantly. 2002 - Hyung-Joo Hong developed a strategy
to incorporate plasticity into ADAMS to make model more robust. Applied this concept to a vehicle shipping
simulation This study implements the strategy,
benchmarks it, and defines its further development.
-
Test Procedure
Front Steered Wheel Impact Wheels steered to
full lock, vehicle placed on dollies
Vehicle dragged into Curb
Test Vehicle
Curb
Direction of Vehicle Travel
-
Test versus Analysis
Test High Impact Force Measurements:
vulnerable to Error Hardware availability
Analysis Requires a very refined model to represent
structural compliance Performed well ahead of Hardware
-
Analysis: FE versus MBD Approach
FE Approach Better representation of structural
compliance including plastic deformation Requires well-defined FE model and MBD
model, which takes long to get reasonable results
MBD (Multi-Body Dynamics) Approach Very quick to get a result Limitation of Representing Structural
Compliance
-
Curb Impact ADAMS Model
Full Vehicle ADAMS model, rigid bodies and connections.
Vehicle stationary, tires on ice. Large mass curb moved perpendicularly
into steered wheel vertical plane. Contact Model between Curb and
Tire/Wheel
-
Standard Model Results
A North American Production Car
TierodF/A Ball Joint
Lateral Ball Joint
Test 12280 17220 26225Original Model 11150 21480 27355
% Difference -9.20% 24.74% 4.31%
Peak force in Newtons
5 mph Peak Force Results
TierodF/A Ball Joint
Lateral Ball Joint
Test 16420 19800 24610Original Model 14400 30690 43720
% Difference -12.30% 55.00% 77.65%
Peak force in Newtons
7 mph Peak Force Results
-
Opportunities for Improvement
Does not capture local effects Vehicles have experienced plastic
deformation during physical test Predicted loads very high
Need to add local plastic deformation
-
Force Versus Deflection Curve
Force
Deflection
Bushing Linear RateBushing Linear Rate
Bushing Ground OutBushing Ground Out
Structural FlexibilityStructural Flexibility
PlasticityPlasticity
Rigid Body Analysis
Flex Body Analysis
Elastic Plastic Analysis
Inaccurate Analysis
-
Plasticity Implementation
Typical Elastic-Plastic load-deflection curves from FE analysis
Force
Deflection
Elastic Limit
-
Plastic Model Results
TierodF/A Ball Joint
Lateral Ball Joint
Test 12280 17220 26225Baseline (Rigid Cradle) 11150 21480 27355Plasticity Model 11170 18400 22220% Difference Plasticity to Test -9.00% 6.90% -15.30%
Peak Force in Newtons
5 mph Peak Force Results
TierodF/A Ball Joint
Lateral Ball Joint
Test 16420 19800 24610Baseline (Rigid Cradle) 14400 30690 43720Plasticity Model 15100 21700 23800% Difference Plasticity to Test -8.00% 9.60% -3.30%
Peak Force in Newtons
7 mph Peak Force Results
-
Results Comparison 5 MPH
-
Results Comparison 5 MPH
-
Results Comparison 5 MPH
-
Results Comparison 7 MPH
-
Results Comparison 7 MPH
-
Results Comparison 7 MPH
-
Conclusions
Predicted loads correlate with measured data very well
Less than 5 minute run time for a typical analysis
Accuracy improvement achieved without increasing simulation time (FE analysis)
More design iterations possible in the analysis world
-
Contact Details
EMEA05-051Dynamic Front Wheel Curb Impact Study
Robert L. GeislerGeneral Motors - North American Product
DevelopmentEngineering Group Manager Chassis [email protected]