Study On The Influence Of Wheel Polygon On Dynamics Of High Speed Train And Fatigue Life Of Axle Box Bolts

With the rapid development of China's high-speed railways and the continuous improvement of operating speeds,the safety and reliability of high-speed trains have become increasingly prominent,and the problem of wheel polygon wear is one of them.This paper takes a high-speed EMU in China as the research object,and focuses on dynamic response of the vehicle under the influence of wheel polygons,and the relationship between the fatigue life of the axle box bolts.The specific research contents are as follows:(1)According to the structure and performance parameters of a certain type of EMU in China,the simulation model of multi-rigid system dynamics is established by using Simpack software.The model considers the nonlinear characteristics of the EMU suspension parameters and the periodic wheel-rail vertical impact vibration under the influence of wheel polygon wear.(2)The effects of speed grade,polygon amplitude and polygon order on vehicle dynamics performance are calculated.It is found that the first-order wheel polygon has the worst stationarity in the low-order polygon range;In the case of considering only the vertical force of the order of the wheel and rail,the vertical force of the wheel rail increases as the order of the polygon increases;When the polygon reaches a certain order,the excitation frequency of the polygon approaches the shaking frequency of the wheel pair,and thus resonance occurs,and the vertical force of the wheel and rail rapidly exceeds the safety limit;The derailment factor is proportional to the amplitude of the wheel polygon,but is still within safe limits.(3)The power spectral density(PSD)function obtained by dynamic simulation is used to solve the stress response of the axlebox assembly,and the fatigue life of the axle box bolt is evaluated by combining the fatigue cumulative damage theory and the S-N curve of the material.The calculation results show that the wheel polygon will affect the fatigue life of the axle box bolt,and the life of the axle box bolt will decrease rapidly as the order and amplitude of the polygon increase.