Analysis of dynamic mechanism and global response of vehicle shimmy system with multi-clearance joints

Joints with clearance always exist in steering mechanism of vehicles due to the machining tolerances, deformations and wear, which should not be neglected in modeling and analysis of vehicle shimmy system. Based on Lagrange equation method, a six-DOF dynamic model of vehicle shimmy system with consideration of multi-clearance joints was established. The model of movement pairs with clearance was built based on Hertzian contact law. The nonlinear cornering force of pneumatic tire was described based on PAC2002 tire model, and its parameters were obtained by an identification method based on experimental data. Then numerical examples were employed to evaluate the dynamic response of the shimmy system. The influence of multi-clearance joints on the response of shimmy was analyzed, and it is compared with that of one clearance joint. The acting mechanism of contact force between movement pairs was investigated, and global dynamic analysis was carried out by using point mapping method. Moreover, the dynamic mechanism for vehicle shimmy was investigated based on energy input. The conclusions can provide theoretic evidence for attenuation of vehicle shimmy, especially for those in-service vehicles.