Study On Hopf Bifurcation Characteristics Of Vehicle Shimmying System Concluding Dry Friction

The vehicle is a complex mechanism system and a variety of reasons may cause the shimmy, related studies have shown that it belong to Limit cycles induced by Hopf bifurcation thus the vehicle can’t work properly. Dry friction is an important nonlinear factor of vehicle shimmy system. The hysteretic effect may lead the shimmy system present multiple limit cycles responses from degenerate Hopf bifurcation. Previous research of vehicle shimmy is confined to the front axle. As for the entirety vehicle, the research is less. Thus it is necessary to research the effects of the dry friction on Hopf bifurcation characteristics of vehicle vibration system.1. A multiple degrees of freedom light truck shimmy model is established. Using nonlinear dynamical theories, critical speed of the prototype vehicle is found and the stability of limit cycles is confirmed.2. The self-excited shimmy system was calculated with the use of IHB theories and the influence of the vehicle parameters on the shimmy system is analyzed. Numerical calculation results show IHB method is reliable and accurate.3. The Coulomb, Stribeck, Hysteresis loop and Wojewoda dry friction model are introduced into the light truck shimmy system to study the influence of different dry friction models on vehicle self-excited shimmy system. The results show that the last two kinds of dry friction model can induce multiple limit cycles.4. The influence of the dry friction torque and automobile cargo capacity on vehicle shimmy system with Wojewoda dry friction was researched, The results show that the shimmy vibration and can be restrained by increasing both dry friction torque or automobile cargo capacity.