轮轨型面匹配对钢轨亚表面抗疲劳裂纹扩展影响

Effect of wheel-rail profiles on sub-surface fatigue crack growth resistance

以标准轮轨型面LMA-60N为对象,分别建立直线运行工况和曲线运行工况下新轮新轨、新轮磨耗轨和磨耗轮磨耗轨匹配关系的6组仿真模型,计算得到钢轨相应的等效应力分布。在焊接钢轨亚表面危险部位引入裂纹并基于Paris理论进行疲劳裂纹扩展寿命分析,以评估轮轨磨耗状态下其型面匹配对钢轨亚表面抗疲劳裂纹扩展能力的影响。研究结果表明:轮轨磨耗对钢轨表面损伤的影响比亚表面的大,且钢轨亚表面2~3 mm深处的裂纹扩展是剪切应力引起的Ⅱ型、Ⅲ型共面剪切型扩展,其深度范围等效应力也最大;直线运行工况更适合新轮新轨型面匹配运行,该型面匹配下钢轨亚表面裂纹扩展速率最慢,扩展寿命最长;曲线运行工况下更适合磨耗轨型面,曲线段磨耗轮与磨耗轨匹配时,钢轨亚裂纹扩展速率最小,扩展寿命最长。

Based on the standard wheel-rail profile LMA-60N,six groups of finite element models of the matching relationships of standard wheel and rail,standard wheel and worn rail,worn wheel and worn rail were established under the service conditions of straight line and curve,respectively.The equivalent stress distributions of the rail were calculated,and the cracks were introduced into the most dangerous location of the welded rail subsurface.To evaluate the effect of wheel-rail profile matching on anti-fatigue crack propagation of rail subsurface under wear condition,the fatigue crack propagation was analyzed based on the Paris formula.The results show that the damage to rail surface caused by wheel-rail wear is larger than that of rail subsurface,and the crack propagation in the depth of 2-3 mm of the rail subsurface is type II and III coplanar shear propagation caused by shear stress,and the equivalent stress of the depth range is also the maximum.The straight line condition is more suitable for the matching operation of standard wheel-rail profile.During the matching of the profile,the crack growth rate of the rail subsurface is the slowest and the growth life is the longest.It is more suitable for worn rail profile under curve condition.When the worn wheel-rail matches,the rail subsurface crack growth rate is the smallest and the fatigue life is the longest.