Analysis of fatigue damage of frame under different influence parameters

Abstract The subway vehicle’s frame is crucial to its operational integrity. However, it faces potential fatigue damage due to the transmission of wheel-rail impact loads. To address this, a comprehensive study is conducted, establishing a dynamic model that considers the interaction between the vehicle and the track. This model incorporates the irregularities present in welded joints as the primary source of impact load excitation. The research is carried out from two aspects, welded joint irregularity and running speed. The results show that the wheel-rail impact force can be transmitted upward to the frame and excite the 46.3 Hz mode and 55.5 Hz mode of the frame, resulting in vibration fatigue damage. Lowering the vehicle’s running speed has been proven effective in mitigating damage caused by impact on the frame. Additionally, it reduces the maximum wheel-rail vertical force, diminishes the wheel unloading rate, and enhances the overall wheel-rail vibration environment. Reducing the fastener stiffness can effectively reduce the damage caused by wheel-rail impact on the frame.