Finite Element Analysis Of Wheel-rail Thermal-contact Coupling

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.