Impact of wheel polygonization on vehicle vibration and wheel-rail interaction forces

This study systematically analyzes the influence mechanism of high-order wheel polygon (20th order) on the dynamic response of high-speed wheel-rail system, which is relatively under-attended in the existing studies (compared with the common 12th order and lower polygons). By establishing a rigid-flexible coupled vehicle-rail dynamics model, we focus on the wheel-rail force fluctuation characteristics and body vibration law of the 20th-order polygon at different amplitudes under the working condition of 350-400 km/h. The time-frequency domain analysis shows that the 20th-order polygon has a significant influence on the dynamic response of high-speed wheel-rail system. The time-frequency domain analysis shows that the 20th-order polygon excites the high-frequency vibration of the wheelsets (60-84 Hz band), which leads to a significant increase in the dynamic amplitude of the vertical wheel-rail force and triggers the phenomenon of track jumping (the peak value of the vertical acceleration of the wheelsets reaches 89 m/s 2 ). It is shown that the wheel-rail force fluctuations induced by the 20th-order polygon are enhanced by about 42% compared with the 12th-order condition when the vehicle speed is increased to 400 km/h, and at the same time, a flexible mode resonance of the vehicle body is induced, which is a phenomenon less frequently discussed in the existing studies on low-order polygons. The coupled velocity-order-amplitude influence law is proposed through parametric analysis, and the results show that the amplitude of the 20th-order polygon needs to be controlled below 0.05 mm in order to effectively avoid the risk of rail jump. This study provides a theoretical reference for the optimization of the maintenance standard of high-speed rail wheel polygons, and suggests a monitoring strategy for high-order polygons.