滚滑接触下钢轨热力耦合分析

THERMO-MECHANICAL COUPLING ANALYSIS OF RAIL IN ROLLING-SLIDING CONTACT

采用热弹塑性有限元法,对滚滑接触状态下的钢轨进行热力耦合分析,计算钢轨接触区附近的温升和应力/应变,并分析蠕滑率对它们的影响。有限元模型中,考虑材料参数随温度的变化,通过在钢轨表面上移动边界条件来模拟车轮的移动。分析结果表明:热影响区主要在很薄的钢轨表层;钢轨表层温升和热应变均随着蠕滑率的增大而增大。热载荷在钢轨表层产生的周向和轴向残余应力表现为拉应力,其在蠕滑率小时有减小机械载荷产生的残余压应力作用;在蠕滑率较大时热响应对残余应力和残余应变影响明显,且当蠕滑率增大到一定值时,考虑热影响时热力耦合作用下的周向残余应力和轴向残余应力都表现为拉应力,而不考虑热影响时二者表现为压应力,随着蠕滑率的继续增大,考虑热影响时的残余应力和残余应变随之增大。

A thermo-mechanical coupling analysis of the rail under a rolling-sliding state is conducted by the thermo-elasto-plastic finite element method. The temperature rise and the stress/strain near the wheel-rail contact patch of the rail are calculated. The effect of the wheel-rail creepage is also investigated. The temperature-dependent material properties are taken into consideration in the finite element model. The movement of boundary conditions of the rail surface is used to simulate the movement of wheels. The results indicate that the thermally affected zone exists mainly in a very thin layer of the material near the rail contact surface. Both the temperature rise and thermal strain increase with increasing the creepage. The circumferential and axial residual stresses generated by the thermal load in the surface layer of the rail appear to be tensile. The thermal load caused by small creepages can reduce the residual compressive stresses generated by the mechanical load. When the creepage becomes larger, however, the thermal response has a significant influence on the residual stresses and residual strains. As the creepage reaches a certain value, the circumferential and axial residual stresses in the thermo-mechanical case become tensile stresses, while in the mechanical case they appear to be compressive stresses. With further increasing the creepage, the residual stresses and residual strains in the thermo-mechanical case increase as well.