地铁车轮踏面中部滚动接触疲劳机制研究

Study on the mechanism of rolling contact fatigue in the central section of wheel treads for metro vehicles

滚动接触疲劳是地铁车轮常见的一种损伤形式,对车轮的服役安全及其维护具有重要影响。文章针对国内某条地铁线路上地铁车辆车轮出现的滚动接触疲劳问题,通过开展现场调查测试和仿真分析,研究了车轮磨耗形式对车轮踏面滚动接触疲劳的影响。结果表明,在该线路上运行的车轮约42%在踏面中部出现滚动接触疲劳,斜裂纹与水平线的夹角基本在40°~50°,并且出现滚动接触疲劳的车轮普遍存在W型磨耗。在车轮出现W型磨耗后,当车辆通过半径小于600 m的曲线时低轨侧车轮接触位置更加集中,蠕滑力合力方向基本与车轮踏面疲劳裂纹垂直,接触应力显著增大,接触区车轮材料更容易处于棘轮效应区,而且车轮的损伤值是LM型踏面的3倍左右。车轮出现W型磨耗是导致该线路车轮踏面中部出现滚动接触疲劳的根本原因。

Rolling contact fatigue(RCF)is a common form of wheel damage of metro vehicles,which has significant impacts on operational safety and maintenance of wheels.This paper focuses on the RCF observed in wheels used on a metro line in China.On-site investigations and simulation analyses were conducted to examine the influence of various wear patterns on the RCF of wheel treads.The results showed that about 42%of the wheels rolling on this line experienced RCF on the central section of their treads,with oblique cracks forming at angles of approximately 40°to 50°relative to the horizontal plane.Moreover,these wheels exhibiting RCF typically displayed W-shaped wear patterns.Increased contact position concentration was noted at the low rail side wheels with a radius of less than 600 m when W-shaped tread wear on wheels,resulting in creep force resultants roughly perpendicular to the fatigue cracks on the wheel treads,and a significant increase in contact stress.As a result,the wheel material in the contact area was more likely to fall into the ratcheting zone.The damage values for these wheels were about two times higher than those with LM treads.To sum up,W-shaped wear on wheels is identified as the primary cause of RCF in the central section of wheel treads for vehicles operating on this line.