Abstract: Huge danger to security and stability caused by nonlinear vibration of automotive steering occurs during vehicle running, so, it’s very important to reduce the vibration and analyze the parameters acting on system. In order to analyze the issue in the round and eliminate vibration reasonably, four degrees of freedom equivalent nonlinear dynamic model of independent suspension automotive steering is established which includes some important nonlinear factors, e.g. clearance, coulomb friction of automotive steering and lateral force. Going with analyzing Hopf bifurcation of multi-DOF system self-excitation vibration concretely, influence of clearance and coulomb friction on critical speed of vehicle and limit cycle amplitude after Hopf bifurcation is discussed in detail and validated by numerical method. Another research is developed on stability of balanceable position and its stable time. The rule derived from the numerical simulation using different nonlinear conditions has instructive significance to avoiding vibration and controlling Hopf bifurcation behavior of automotive steering.

Key words: Coulomb friction nonlinearity, Equivalent nonlinear vibration model, Hopf bifurcation characteristic, Independent suspension automotive steering