【作者】 齐万明；

【导师】 张军；

【作者基本信息】 大连交通大学 ， 车辆工程， 2010， 硕士

【摘要】 车轮踏面的擦伤和剥离是机车车辆运行过程中常常会遇到的问题。车轮和钢轨之间滑动所产生的摩擦热是引发轮轨擦伤的主要因素。踏面制动车轮温升会达到很高的温度,车轮与钢轨瞬态接触过程中由于存在较高的温差,就会对轮轨应力大小以及分布区域产生影响。探索轮轨接触温升和热应力规律对研究车轮和钢轨的热损伤和剥离具有很大的意义。本文建立了轮轨三维热接触耦合有限元模型,分别是锥型、磨耗型踏面机车车轮和LM型车辆车轮分别在60 kg/m钢轨上滑行,磨耗型踏面机车车轮滚动过程中的有限元模型。主要利用大型有限元软件MARC进行热接触耦合计算。考虑材料非线性、轴重、速度和摩擦系数的变化情况对车轮和钢轨的温度和应力分布的影响,比较了纯机械载荷作用下和热载荷作用下应力分布的差异。通过对轮轨擦伤问题的分析,得出锥型踏面机车车轮滑行时温度和应力都高于磨耗型踏面机车车轮,这说明锥型踏面机车车轮对车轮和钢轨的热损伤比磨耗型踏面机车车轮要大;机车车轮滑行时对车轮和钢轨的热损伤比车辆车轮要大。材料非线性对于在计算轮轨热接触耦合过程中的影响不可忽略;轮轨的应力和温度都随着轴重和速度的增大而升高。车轮最大应力区域与实际擦伤区域形状相似,范围略小。针对车轮滚动过程中轮轨剥离问题的瞬态分析,得出随着制动力矩的增大,车轮和钢轨的最大应力都升高;随着轴重的增大、踏面温度的升高和表面硬化层的出现都会使轮轨的最大应力逐渐增大;车轮的最大应力分布区域集中在车轮表面0~3mm左右,这与实际裂纹区域相吻合;接触力对轮轨应力大小的影响远大于热载荷对轮轨应力大小产生的影响。较大的接触应力导致车轮表面硬化层碎裂,产生裂纹,进而导致踏面剥离的发生。本文计算方法和结果将为探讨车轮踏面擦伤和剥离提供理论参考。更多还原

【Abstract】 It is a common problem that the tread scratch damage and shelling when locomotive and vehicle are running. The friction heat between wheel and rail for sliding is the main factor of scratch damage. Tread brake will lead to a high temperature for wheel. There is a big difference in temperature during transient contact of wheel and rail, which will have impact on the contact stress of wheel and rail and their distribution areas. It is greatly significant for investigating the thermal damage and shelling of wheels and rails to explore the laws of contact temperature and thermal stress between wheel and rail.The models of three-dimensional finite element and thermal coupled contact are built which including cone type tread, wear type tread of locomotive wheel and LM type tread of vehicle wheel sliding on the 60 kg/m rail. The models also include wear type tread of locomotive wheel rolling in braking process. Thermal-contact coupled contact was simulated considering the factors of the material nonlinearity, axle load, speed and friction coefficient on the temperature and stress distribution of the wheel and rail by large-scale finite element software named MARC. The variations of stress distributions were compared between mechanical loads condition and thermal loads condition.The result show that the temperature and stress generated from cone type locomotive wheel tread when sliding are higher than that generated from wear type. So the thermal damage of wheel-rail with cone type tread is more serious than that with wear type. The thermal damage of the wheel and the rail under the locomotive’s sliding is more serious than that under the vehicle’s sliding. Material nonlinearity for the thermal coupled contact cannot be neglected .The stress and the temperature of wheel and rail are both increased as axle load and speed increasing. The shape is similar comparing the maximum stress area with actual scratch area, but the range is smaller with the former.As for the instantaneous analysis of shelling problem, it is found that the maximum stress of the wheel and rail increases with the braking torque, axle load and tread temperature increasing under the mechanical load condition. The maximum stress of the wheel and rail also increases with surface hardened layer producing. The Maximum-stress located under the surface 0-3 mm . This is consistent with the actual crack area. The effect of contact force to wheel-rail contact stress is much more obvious than that of thermal effect. The higher stress leads to fragile cracking for the surface hardness layer, therefore the crackle generated, which leads to the shelling.The research method and results of this paper provide a theoretical reference for reducing the wheel tread thermal damaged and shelling.更多还原