Analysis of shimmy characteristic based on temperature effects and steering linkage clearance for vehicle

Abstract: Vehicles work in outdoor environments to deliver goods or people, while the ambient temperature varies in different seasons or different regions. Since the process parameters of the kinetic pair in vehicle steering mechanisms are usually designed based on the domestic temperature of 20oC, the temperature variation usually leads to mechanical deformation of components of kinetic pairs in vehicle steering mechanisms, and as a result, the deformation of the components may change the kinetic and dynamic characters of the kinetic pair. Consequently, the dynamic response of the steering system may vary if the vehicle is exposed to different temperature working conditions. As a result, the dynamic behavior of the vehicle shimmy system may be influenced by the temperature effect. Actually, some cases have been reported that the dynamic response of the steering system of certain vehicles varied in different seasons or in different regions. To evaluate the influence of temperature effects on the dynamic response of the vehicle shimmy system with clearance in the steering mechanism, and to prevent the potential deviation of the dynamic response of the steering system from its original design goal, the dynamic behavior of the vehicle shimmy system with clearance in steering linkage with consideration of temperature effect is discussed. Based on thermal elasticity, thermal deformation of kinetic pair components is calculated, and the influence of temperature effects on clearance of revolute kinetic pair was analyzed. As a result, interaction forces between the kinetic pair components with consideration of temperature effect is re-evaluated, and the sub dynamic model of the kinetic pair with clearance with consideration of temperature effect is available. Consequently, a vehicle with dependent suspension was employed as an example, and the dynamic model of the vehicle shimmy system with clearance in steering linkage with consideration of temperature effect is presented. Based on this model, the dynamic behavior of the vehicle shimmy system with clearance with consideration of temperature effects was discussed. Bifurcation characteristics and initial value characteristics of the system were analyzed with numerical examples, and the coupling influences of the temperature and other system parameters, such as vehicle speed, etc, on the global dynamic behavior of the vehicle shimmy system were evaluated. The results show that the temperature and other parameters can make a significant coupling contribution to the dynamic response of the vehicle shimmy system. The change of ambient temperature may lead to significant variation of the dynamic behavior of the system, and it seems that the influence is likely to be more significant at a higher speed range than that at lower speed range. For those examples presented in the paper, the dynamic behavior of the system is significantly affected by temperatures in the speed range 85km/h~110km/h, while it remains stable in lower speed ranges. The method and conclusions presented in this paper may provide theoretical basis for improvement of a vehicle shimmy control with consideration of temperature effect, and they are helpful to perfect the modeling theory of vehicle shimmy system.