轮轨滚动接触和制动热负荷耦合作用对重载车轮踏面裂纹萌生寿命的影响

Coupling Effect of Wheel-Rail Rolling Contact and Braking Thermal Load on Crack Initiation Life of Heavy Haul Wheel Tread

在长大下坡道循环制动条件下,采用列车纵向动力学、三维有限元和疲劳损伤分析联合仿真方法,综合考虑车轮踏面在制动摩擦过程中瞬态非均匀热流分布和轮轨滚动接触,计算重载车轮踏面裂纹萌生寿命。采用有限元软件Abaqus建立闸瓦—车轮三维瞬态热—机耦合有限元模型并在试验验证其准确性的基础上,以大秦线某段典型长大下坡道为例,研究制动热负荷和轮轨滚动接触耦合作用对车轮踏面裂纹萌生的影响。结果表明:制动热负荷或轮轨滚动接触单独作用不是导致车轮踏面出现裂纹的主要原因,而轮轨滚动接触和坡道制动热负荷的耦合作用才是导致运营车轮裂纹萌生的主要因素;踏面温度对轮轨滚动接触踏面裂纹萌生寿命的影响较大,车轮材料采用CL70钢、踏面温度超过250℃后,踏面裂纹萌生寿命显著降低。

Under the condition of the cyclic braking on long heavy down grade,the crack initiation life of heavy haul wheel tread was calculated by the combined simulation method of train longitudinal dynamics,three-dimensional finite element and fatigue damage analysis,taking into account the transient non-uniform heat flow distribution of wheel tread and wheel-rail rolling contact during braking friction.Based on the three-dimensional transient thermal-mechanical coupling finite element model of brake shoe and wheel established by finite element software Abaqus and its reliability verified by the brake test,taking a typical long heavy down grade of Daqin Railway as an example,the coupling effect of braking thermal load and wheel-rail rolling contact on the crack initiation of wheel tread was studied.Results show that braking thermal load or wheel-rail rolling contact alone is not the main cause of wheel tread cracks,while the coupling effect of wheel-rail rolling contact and ramp braking thermal load is the main factor leading to the crack initiation of operating wheel.The tread temperature has a greater influence on the crack initiation life of wheel-rail rolling contact tread.When the wheel material is CL70 steel and the tread temperature exceeds 250℃,the crack initiation life of the tread decreases significantly.