铁路车轴微动磨损对微动裂纹扩展的影响研究

Investigation on the Effect of Fretting Wear on Fretting Crack Propagation of Railway Axles

仿真计算了磨损/未磨损情况下不同深度微动裂纹尖端的等效应力强度因子ΔK_(eq),并从接触状态和应力分布两个角度阐述了影响机理。对于铁路车轴,考虑微动磨损时计算的ΔK_(eq)更大,微动磨损促进了微动裂纹的扩展。当微动裂纹深度不大于2mm时,磨损/未磨损情况下计算的ΔK_(eq)相对误差大于7%。由于微动磨损,车轴轮座配合边缘及附近的区域出现了张开区,释放了过盈配合导致的压应力。此外,微动磨损在车轴轮座内部引入的应力集中增加了配合面下方的应力场。这两方面的共同作用促进了微动裂纹向车轴深度方向扩展。微动磨损对裂纹扩展的影响不能忽略,建议在车轴微动裂纹剩余寿命的评估中考虑微动磨损的影响。

In this paper,the equivalent stress intensity factorsΔK_(eq) of fretting crack tips at different crack depths in the case of worn/unworn were calculated.Thereafter,the influence mechanism was clarified from two perspectives of contact status and stress distribution.For railway axles,ΔK_(eq) was greater for the worn axles,which promoted the fretting crack propagation.When the crack depth was not greater than 2 mm,the relative error ofΔK_(eq) calculated under the worn/unworn condition was greater than 7%.Owing to fretting wear,an open zone appeared near the contact edge of the wheel seat,releasing the compressive stress induced by the interference fit.In addition,the stress concentration introduced by fretting wear increased the stress field below the contact surfaces.The combined effect of these two aspects promoted thefretting cracks propagation to the depth direction of the axle.The influence of fretting wear on crack propagation cannot be neglected,and it is recommended to take the influence of fretting wear in evaluating the remaining life of fretting cracks.