高速铁路钢轨擦伤形成影响因素

基于ANSYS显式动力分析建立了三维瞬态轮轨接触力-热耦合有限元模型，考虑了温度对热-弹塑性材料参数的影响；以初始温度30 ℃、轴重16 t、初始速度300 km·h^-1、滑滚比30%工况为例，研究了车轮在经过钢轨典型断面前、中、后3个时刻下钢轨踏面的接触压力、有效塑性应变、温度分布及其变化特征；在此基础上，进一步分析了列车轴重、钢轨踏面状态、列车牵引和制动状态对钢轨踏面最大温升与最大接触压力的影响，并基于钢轨马氏体白蚀层的形成机制讨论了钢轨擦伤的形成机理。研究结果表明：在本文计算工况下，钢轨踏面最大接触压力为1 186.43 MPa，出现在接触区中心位置，车轮通过后钢轨内部存在部分残余热应力和机械应力，钢轨最大有效塑性应变为0.028 2，最大温升为554.55 ℃；随着列车轴重从12 t增大至16 t，钢轨最大温升由339.89 ℃增大至402.79 ℃；钢轨踏面摩擦因数由0.2增大至0.6时，钢轨最大温升由230.93 ℃增大至519.25 ℃；滑滚比由10%增大至40%时，车轮制动和牵引引起的钢轨最大温升分别由264.52 ℃和362.10 ℃增大至700.46 ℃和819.61 ℃，相同滑滚比条件下，牵引工况引起的钢轨最大温升大于制动工况引起的钢轨最大温升，其中在滑滚比增大至40%时，制动和牵引状态下钢轨踏面最高温度分别为700.46 ℃和819.61 ℃，钢轨最大温升均超过相变温度，可导致钢轨踏面产生马氏体白蚀层，从而形成钢轨踏面擦伤。

Influencing factors of rail burn formation for high-speed railway

The ANSYS explicit dynamic analysis was employed to build a three-dimensional transient wheel-rail contact mechanical-thermal coupling finite element model with the influence of temperature on the thermo-elastoplastic material parameters taken into consideration. Under the working conditions of an initial temperature of 30 ℃, an axle load of 16 t, an initial speed of 300 km·h-1, and a slip-to-roll ratio of 30%, the contact pressure, effective plastic strain, temperature distribution and its variation characteristics of the rail tread were studied at the earlier, middle, and later moments when the wheel passed by the typical rail sections. On this basis, the influences of the train axle load, rail tread state, as well as the train traction and braking states on the maximum temperature rise and maximum contact pressure of the rail tread were further analyzed, and the formation mechanism of rail burn was discussed on the basis of the formation mechanism of the martensite white etching layer of rail. Research results show that under the calculation conditions of this paper, the maximum contact pressure of the rail tread is 1 186.43 MPa, which appears at the center of the contact zone. The residual thermal and mechanical stresses inside the rail can be found after the wheel passes. The maximum effective plastic strain of the rail is 0.028 2. The maximum temperature rise is 554.55 ℃. When the train axle load increases from 12 t to 16 t, the maximum temperature rise of the rail increases from 339.89 ℃ to 402.79 ℃. When the friction coefficient of the rail tread increases from 0.2 to 0.6, the maximum temperature rise of the rail increases from 230.93 ℃ to 519.25 ℃. When the slip-to-roll ratio increases from 10% to 40%, the maximum temperature rises of the rail caused by the wheel braking and traction increase from 264.52 ℃ to 700.46 ℃ and from 362.10 ℃ to 819.61 ℃, respectively. Under the same slip-to-roll ratio, the maximum temperature rise of the rail caused by the traction condition is more significant than that caused by the braking condition. In particular, when the slip-to-roll ratio increases to 40%, the maximum temperatures of the rail tread are 700.46 ℃ and 819.61 ℃ under the braking and traction conditions, respectively. The maximum temperature rise of the rail is higher than the phase transition temperature. As a result, a martensite white etching layer on the rail tread is formed to develop rail burn on the rail tread.