基于细观尺度粗糙轮轨接触蠕滑特性数值分析

为了进一步考虑粗糙表面对轮轨蠕滑的影响,从微凸体的微米尺度跨越到米的尺度,着力于摩擦的物理学本质,建立干摩擦工况下的轮轨蠕滑力的二维动态计算模型。通过微凸体接触与断开来模拟轮轨接触的滚滑运动,讨论不同速度、蠕滑率、轮轨表面粗糙度参数等因素对轮轨黏着系数的影响,对每个因素造成的轮轨牵引系数的变化进行数值分析。在中低速情况下,通过对线路测量数据和实验室JD对滚机数据与模型计算结果的对比,验证了模型的有效性。结果表明随着速度的增大,黏着系数随之下降;适当增加轮轨表面粗糙度能提高轮轨间的黏着系数;同时以非人为划分的方式重现接触斑内牵引系数变化的过程,从黏着区到滑动区的过渡过程。

Numerical Analysis of Wheel/Rail Adhesion on the Rough Surface Based on Meso-scale

In order to consider the effect of the rough surface on the creep between wheel and rail, a two-dimensional dynamic calculation model of wheel rail adhesion under dry friction condition is established from the micrometric scale to the meter scale to address the physical nature of friction. The sliding/rolling between wheel and rail is simulated through contact and disconnection of the asperities, and the effects of different speed, creepage, surface roughness parameters of the wheel and rail on the adhesion coefficient between wheel and rail are discussed. At low and medium speed, the effectiveness of the model is verified by comparing the filed measured data and the data from JD test machine with the results of the model. The results show that the adhesion coefficient decreases with the increase of velocity; the adhesion coefficient between wheel and rail can be improved by properly increasing the surface roughness of wheel and rail; the model reproduces the circle process of the traction coefficient on the contact patch and the transient process from stick area to sliding area on the contact patch by the way of unartificial division.