考虑非对称轨底坡的轮轨滚动接触应力分析

Analysis of Wheel/Rail Rolling Contact Stress Considering Asymmetric Rail Cant

研究目的:针对我国地铁线路钢轨因施工误差导致的非对称轨底坡处易出现疲劳伤损现象,利用我国地铁车辆常用的LM型面与CHN60钢轨,基于轮轨接触几何关系和Kalker三维非赫兹弹性体滚动接触理论及其数值程序CONTACT,分析非对称轨底坡对轮轨接触几何参数和轮轨接触力学特性的影响,揭示引起轮轨滚动接触疲劳的原因。研究结论:(1)随着轨底坡的减小,轮轨接触点对分布趋向于轨距角一侧,接触点对分布范围变窄,且轮轨接触斑面积减小,滑动区增大;(2)横移量小于4 mm时,右轨侧1/30、1/40、1/50三种轨底坡下的最大法向接触应力相差不大,但均明显高于轨底坡为1/20的值;在5~8 mm横移量范围内时,相同横移量下轮轨接触应力随着轨底坡的减小而增大;(3)同一横移量下轮轨体内最大等效应力值随着轨底坡的减小而增大,右轨侧轨底坡从1/20减小至1/50时最大等效应力均增加了60%左右,且等效应力沿纵向分布范围变窄,沿深度方向影响范围变小,等效应力作用趋于集中;(4)轨底坡的减小引起轮轨表层接触应力增大及轮轨体内等效应力增加,可能引起轮轨材料从表层到深度领域内的疲劳破坏,缩短轮轨的使用寿命;(5)本研究成果可为我国地铁线路检测、维修及轨底坡设置等提供参考。

Research purposes: With a view to the phenomenon of fatigue damage at the asymmetric rail cant caused by the construction error of subway rail in China,the wheel profile is of the type LM and the rail is the standard CHN60,both of them are commonly used in subway. Based on the wheel-rail contact geometry relationship and Kalker three-dimensional non-Hertzian rolling contact theory and its numerical program CONTACT,the influence of asymmetric rail cant on the wheel-rail contact geometric parameters and wheel-rail contact mechanical properties is analyzed and the cause of wheel/rail rolling contact fatigue is revealed.Research conclusions:( 1) With the decrease of rail cant,the distribution of the wheel-rail contact points tends to one side of the gauge angle,the distribution range of the contact points becomes narrower,the area of the wheel-rail contact spot decreases and the slip area increases.( 2) When the lateral displacement is less than 4 mm,the maximum normal contact stress at the rail cant of 1/30,1/40 and 1/50 on the right rail side has little difference,and is obviously higher than that at the rail cant of 1/20. In the range of 5 mm to 8 mm lateral displacement,the wheel-rail contact stress increases with the decrease of the rail cant.( 3) Under the same lateral displacement,the maximum equivalent stress in wheel-rail body increases with the decrease of rail cant. When the right rail cant decreases from 1/20 to 1/50,the maximum equivalent stress increases by about 60%,and the distribution range of the equivalent stress along the longitudinal direction becomes narrower,the influence range along the depth direction decreases,and the effect of the equivalent stress tends to be concentrated.( 4) The decrease of rail cant will increase the contact stress of wheel/rail surface and the equivalent stress in wheel/rail body,which may cause fatigue failure of wheel/rail material from surface to depth,and shorten its service life.( 5) The research results can provide references for the detection,maintenance and rail cant setting of subway line in China.