30t轴重重载铁路轮轨滑动接触引起的钢轨热相变分析

Analysis of Rail Thermal Phase Transformation due to Wheel-rail Sliding Contact for Heavy-haul Railway with 30t Axle-load

轮轨接触热损伤是重载铁路轮轨结构的主要失效形式之一。当重载列车机车加速牵引时,轮轨接触界面间发生相对滑动,轮轨相对滑动会导致轮轨接触区出现较高的接触温升,这种接触温升积累到车轮和钢轨材料的相变时会发生相变,从而导致轮轨接触表面的擦伤、裂纹和剥离等。本文将钢轨看作是弹性半空间体。首先利用轮对切片投影法计算轮轨接触几何关系,然后利用接触弹性方法计算了轮轨接触斑和法向接触应力,最后将得到的轮轨法向接触应力施加到钢轨弹性半空间模型中,利用Matlab软件编制了轮轨接触热效应分析程序,计算分析了轮轨接触的热效应,并研究了钢轨材料马氏体层产生的厚度、位置及其分布。针对不同的轮对横移量、车轮移动速度、摩擦因数和相对滑动速度进行了钢轨的温度场研究。结果表明:轮轨滑动接触热效应剧烈,温升可以达到奥氏体化临界点,形成脆硬的马氏体。计算结果也表明,利用弹性半空间假设研究轮轨接触热效应问题是可行的。

Thermal damage due to wheel-rail contact is one of the main failure modes of wheel-rail system in heavy-haul railway.When a heavy haul train accelerates,slide may occur on the contact surface between the wheel and the rail,which will lead to higher wheel-rail temperature rise.The rise of the temperature to a certain value will cause the phase change of the wheel/rail materials,which will lead to the cracks,scratches and stripping damage on the surface of the wheel and rail.The rail was viewed as a semi-elastic space.Firstly,a wheelset axial slice projection method was used to calculate wheel/rail contact geometry,then the wheel-rail contact elastic method was used to obtain the wheel/rail contact patch and normal contact stress.Finally,the wheel-rail normal contact stress obtained was applied to the semi-elastic space model of the rail.A computer program to predict the thermal effects of the wheel-rail contact was compiled with Matlab software to analyze the generation location,depth and distribution of the martensite of the rail top.The temperature field of the rail was investigated under the conditions of different wheel-set lateral displacements,different wheel speeds,different friction coefficients and different relative sliding velocity of the wheel-rail system.The results showed that the dramatic thermal effects due to wheel/rail sliding contact may cause the rise of the temperature to austenization to form crisp and rigid martensite.The results also showed that it is feasible to study the thermal effect of the wheel/rail contact using elastic half-space hypothesis.