| Wheel-rail contact relationship is the basic condition for the normal operation of railway vehicles which has the bearing,traction,braking and other important mission on its shoulder.Wheel-rail relationship is the most basic and very complex problem in wheel-rail system of railway vehicles.With the development of high-speed and heavy-haul railway transport,it is significant to analyze the relationship between wheel and rail accurately for the economy and security of railway transport.The wheel-rail contact relationship involves a variety of physical phenomena when the locomotive is running on the rail.When the wheel is running on the rail with bearing huge loads,there is elastic-plastic rolling contact problem between the wheel and rail,which is solid mechanics.The frictional heat due to the contact between wheel and rail should be duly transferred,which is a typical heat transfer problem.When the locomotive is running in high speed,the air around the wheel is flowing rapidly and the rotational wheel is an inducement of air flowing,which is typical of air flow problems.The friction between wheel and rail can cause frictional heat,the air flow around the wheel and rail accelerates the loss of the heat,and the timely dissipation of heat facilitates the interaction between wheel and rail,these three are complementary.Therefore,the wheel-rail contact relationship during the train movement is a typical solid mechanics-heat transfer-fluid mechanics coupling problem.It is significant to develop a numerical method based on the same basis theory for solving the above multidisciplinary coupling problem.In this paper,the finite volume method was used to solve the contact stress field of wheel and rail.The finite volume method is a numerical method based on the conservation principle which has normal discrete scheme and boundary condition processing.The qualitative analysis of the wheel-rail contact relationship was carried out based on the Hertz contact theory,and the generation of the contact spot and the division of the contact spot were described in this paper.Because wheel-rail contact problems are solid statics problems,the solid statics equations and the fluid flow equations were compared to seek the appropriate solid statics equations for finite volume method in this paper,and besides,the equations and boundary conditions were discretized by numerical method.In this paper,the model of wheel-rail contact stress field was established by using unilateral wheel and rail.Based on the unilateral wheel and rail as the model,the stationary model of wheel and rail is established and calculated.The results show that the size of the contact spot on the wheel and the size of the contact spot on the rail are basically the same,the contact spots are elliptical.Comparison of the contact spot on the rail and the contact spot calculated by the Hertz theory,the error of semi-long axis and semi-short axis is 5.93 % and 6.32 %,respectively.This shows that the finite volume method for solving wheel-rail contact problems is reliable.At the surface of wheel and rail contact spot,the stress distribution is also elliptical with the contact spots.The stress near the center of the contact spot is larger,and the stress gradually decreases from the center of the contact spot.The size of the contact spot of the wheel and the rail is the same,and the position is also corresponding.The distribution of the stress on the contact spot is also consistent with each other.The stress is transmitted inward from the surface of the contact spot so that the stress near the contact spot is ellipsoidal in space.The average stress of the contact surface of the rail is 708.8 MPa,the maximum contact stress is 951 MPa.The maximum stress is greater than the yield limit of the rail material,which is 883.0 MPa.This part of the stress greater than the yield limit may cause the rail surface pitting,falling off and other failure forms. |
PDF Full Text Request