INFLUENCE OF SHOCK ABSORBER MODEL FIDELITY ON THE PREDICTION OF VEHICLE HALF ROUND PERFORMANCE

Model based design techniques are being used increasingly to predict vehicle performance before building prototype hardware. Tools like ADAMS and Simulink enable very detailed models of suspension components to be developed so vehicle performance can be accurately predicted. In creating models of vehicle systems, often there is a question about how much component detail or model fidelity is required to accurately model system performance. This paper addresses this question for modeling shock absorber performance by comparing a low fidelity and high fidelity shock absorber model.

A high fidelity and low fidelity mathematical model of a shock absorber was developed. The low fidelity shock absorber model was parameterized according to real shock absorber hardware dimensions. Shock absorber force vs. velocity curves were calculated in Simulink. The results from the low fidelity and high fidelity model were compared to shock absorber force vs. velocity test results.

New vehicle designs must meet requirements for maximum driver’s seat acceleration during half round testing. These requirements have created a need for predicting half round performance. The low fidelity and high fidelity shock absorber models were placed in a 7 Degree-of-Freedom vehicle model. Maximum driver’s seat acceleration was calculated and simulation results were compared to half round test results from a prototype vehicle for a 10mph, 8” half round test.