Analysis of Vehicle Chassis Transmissibility of Steering Shimmy and Brake Judder: System Modeling and Validation

This paper describes the development of a simulation technology for analyzing vehicle chassis transmissibility for the vibrations induced by tire-wheel imbalance and brake torque fluctuation. A multi-body simulation model is created for the coupled front chassis system consisting of steering, suspension, floating sub-frame, tire-wheel and a virtual excitation rig. Non-linear elements, such as frictions of joints, displacement-dependent bushings and detailed hydraulic power assist system, are considered. The simulation model is validated extensively by a unique laboratory excitation test in both frequency and time domain under different levels of excitation. Good agreement between simulation and measurement is achieved, and example results are presented.