Influence Of Temperature Effect On Dynamics Of Vehicle Shimmy System With Clearance In Movement Pair Of Steering Linkage Mechanism

Front wheel shimmy is a common and harmful phenomenon. It may cause the violent vehicle vibration, increase the workload of the steering system, aggravate the tire wear, even shorten the parts service life. So as to degrade vehicle’s ride comforta-bility, manoeuvrability and stability, safety and fuel economy.With respect to the front wheel shimmy resulted from clearance in movement pair of steering linkage, the influence of temperature, driving velocity, contact stiffness of clearance movement pair and front wheel alignment on vehicle shimmy is discussed elaborately with bifurcation theories of nonlinear dynamics in this paper.The domestic and international research on front wheel shimmy is reviewed, the previous progress of our research group is summarized and then the necessity to take temperature effect into consideration is presented after the analysis of existing problems in shimmy research. Based on the thermal deformation theories, functional relationship between temperature and clearance is bridged, and the contact model is built with the two-state theory. And then, a four degree of freedom shimmy model considering temperature effect is established, taking account of front axle rolling movement, as well as front wheel and steering tie rod swing movement, with the methods of time-domain figure, phase space, power spectrum analysis and Poincare mapping, the influence of the temperature, driving velocity, contact stiffness of clearance movement and the front wheel alignment on vehicle shimmy is analyzed. It is found that the driving velocity, contact stiffness of clearance movement and front wheel alignment affect the shimmy system to different extent; In the range of specific parameters, the shimmy amplitude is reduced slightly by the rising environmental temperature; On the contrary, when the environmental temperature goes down, the range of shimmy velocity is enlarged mildly, and the shimmy amplitude increases slightly.The point mapping method has been considered to elaborate global analysis on temperature and initial condition. The result indicates that the uncertainty of steering system dynamic behaves has been increased as a result of taking temperature effect into consideration.