三维弹塑性轮轨滑动接触热机耦合分析

为提高轮轨滑动接触热响应分析的准确性，基于Johnson-Cook材料模型，充分考虑含摩擦因数在内多种材料属性的温度相关性、3种热传递方式和轮轨实际廓形，建立了全比例三维弹塑性轮轨滑动接触有限元模型，采用完全耦合法对滑动接触状态下的轮轨进行热机耦合分析；研究了车轮以1 m·s^-1速度沿钢轨滑行0.1 s时的轮轨温度场和应力场分布特性，分析了轴重、相对滑动速度对轮轨接触区温度场的影响，得到了热影响层深度、热影响层宽度、轮轨表层温度随轴重、相对滑动速度的变化关系。分析结果表明：轮轨最大等效应力发生在次表层接触斑中心处，车轮表层最高温度发生在接触斑后半部分中心处，车轮表层最高温度为848 ℃，钢轨表层最高温度为768 ℃，钢轨表层最高温度低于车轮表层最高温度；轮轨热影响层很薄，车轮热影响层深度约为4.22 mm，钢轨热影响层深度约为3 mm；轮轨热影响层深度随轴重增大无明显变化，而宽度随轴重的增大而增大，轮轨热影响层深度随相对滑动速度的增大而减小，而宽度随相对滑动速度增大无明显变化，轮轨表层温度随轴重和相对滑动速度的增大而增大，且相对滑动速度对轮轨热响应影响更大。全比例三维弹塑性轮轨滑动接触有限元模型及热机完全耦合法能够更加准确地预测轮轨滑动接触热响应，对合理开展轮轨热损伤和热疲劳研究具有重要意义。

Thermal-mechanical coupling analysis of three-dimensional elastic-plastic wheel-rail sliding contact

To improve the accuracy of thermal response analysis of wheel-rail sliding contact, on the basis of the Johnson-Cook material model, fully considering the temperature correlation of various material properties including the friction coefficient, three heat transfer modes, and the actual wheel-rail profile, a full-scale three-dimensional elastic-plastic wheel-rail sliding contact finite element model was established. The thermal-mechanical coupling analysis of the wheel-rail in sliding contact state was carried out by using the fully coupling method. The wheel-rail temperature field and stress field distribution characteristics were studied when the wheel slid along the rail at a speed of 1 m·s-1 for 0.1 s, and the effects of the axle load and relative sliding speed on the temperature field of the wheel-rail contact area were analyzed. The variation relationships of the depth of the heat-affected layer, the width of the heat-affected layer, and the temperature of the wheel-rail surface with the axle load and relative sliding speed were obtained. Analysis results show that the maximum equivalent stress of the wheel and rail occurs at the center of the subsurface contact patch, and the maximum temperature on the wheel surface occurs at the center of the rear part of the contact patch. The maximum temperature on the rail surface is lower than that on the wheel surface as the latter is 848 ℃, and the former is 768 ℃. The heat-affected layer of the wheel and rail is very thin, with the depth of the heat-affected layer for the wheel being about 4.22 mm and that for the rail being about 3 mm. The depth of the heat-affected layer for the wheel and rail has no significant change with the increase in the axle load, but the width increases with the increase in the axle load. The depth of the heat-affected layer for the wheel and rail decreases with the increase in the relative sliding speed, but the width has no significant change with the increase in the relative sliding speed. The temperature of wheel-rail surface increases with the increase in the axle load and relative sliding speed, and the relative sliding speed has a greater effect on the wheel-rail thermal response. The full-scale three-dimensional finite element model for the elastic-plastic wheel-rail sliding contact and the thermal-mechanical fully coupling method can more accurately predict the thermal response of wheel-rail sliding contact, which is of great significance for the rational research on the wheel-rail thermal damage and thermal fatigue. 3 tabs, 15 figs, 31 refs.