Abstract
The parameters of traditional yaw dampers are typically determined during the vehicle dynamics design stage based on specific wheel and rail profiles. However, dampers with fixed parameters often struggle to effectively mitigate hunting motions due to the significant variations in wheel-rail contact conditions encountered during operation. Unlike the traditional method of adjusting dynamic damping, the goal of this work is to propose an innovative on-off yaw damper that can realize switchable low and high dynamic stiffness, and thus has the ability to suppress both low-frequency carbody hunting and high-frequency bogie hunting under different wheel-rail conicity conditions. First, the working principle of the damper is detailed, highlighting switchable dynamic stiffness in two selectable modes. A physical model is then developed to study the damper’s dynamic characteristics under different combinations of excitation frequency and amplitude. The results reveal a substantial difference in dynamic stiffness between the two modes, with a 74% variance, while dynamic damping remains largely unaffected. A new parameter, termed dynamic stiffness difference, is introduced to describe the frequency-dependent stiffness property of the damper, and its sensitivity to damper parameters is explored, providing insights for design optimization. Finally, numerical simulations demonstrate that the on-off yaw damper significantly improves both low and high conicity stability, thereby enhancing overall vehicle stability across a wide range of wheel-rail contact conditions.
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