The influences of the lateral motion of a single wheelset running on a tangent railway on the creepages and creep forces between wheel and rail are investigated with numerical methods. ...The influences of the lateral motion of a single wheelset running on a tangent railway on the creepages and creep forces between wheel and rail are investigated with numerical methods. The effect of the yaw motion of wheelset is neglected in the analysis, and Kalker’s theory of three dimensional elastic bodies in rolling contact is employed to analyze the creep forces in the wheel/rail rolling contact with Non Hertzian form.展开更多
Creep forces depend greatly on creepages in the contact area forming between wheel and rail.The creepages are completely determined by the state of ...Creep forces depend greatly on creepages in the contact area forming between wheel and rail.The creepages are completely determined by the state of a wheelset moving on a track.In this paper the contact state of a single rigid wheelset moving on a tangent rigid rail,creepages and their sensitivities to some parameters of contact geometry are analyzed by semi analytical method and numerical method,respectively.Some important ideas will be provided for the studies done on the interactions between wheels and rails at high speed.展开更多
Thermal damage caused by frictional heat of rolling-sliding contact is one of the most important failure forms of wheel and rail. Many studies of wheel-rail frictional heating have been devoted to the temperature fiel...Thermal damage caused by frictional heat of rolling-sliding contact is one of the most important failure forms of wheel and rail. Many studies of wheel-rail frictional heating have been devoted to the temperature field, but few literatures focus on wheel-rail thermal stress caused by frictional heating. However, the wheel-rail creepage is one of important influencing factors of the thermal stress In this paper, a thermo-mechanical coupling model of wheel-rail rolling-sliding contact is developed using thermo-elasto-plastic finite element method. The effect of the wheel-rail elastic creepage on the distribution of heat flux is investigated using the numerical model in which the temperature-dependent material properties are taken into consideration. The moving wheel-rail contact force and the frictional heating are used to simulate the wheel rolling on the rail. The effect of the creepage on the temperature rise, thermal strain, residual stress and residual strain under wheel-rail sliding-rolling contact are investigated. The investigation results show that the thermally affected zone exists mainly in a very thin layer of material near the rail contact surface during the rolling-sliding contact. Both the temperature and thermal strain of rail increase with increasing creepage. The residual stresses induced by the frictional heat in the surface layer of rail appear to be tensile. When the creepage is large, the frictional heat has a significant influence on the residual stresses and residual strains of rail. This paper develops a thermo-meehanical coupling model of wheel-rail rolling-sliding contact, and the obtained results can help to understand the mechanism of wheel/rail frictional thermal fatigue.展开更多
Due to extensitve application of bridge structure on high speed railway line, it is necessary to consider comprehensively the common effect of the train, the track and the bridge. By forming an integrated large system...Due to extensitve application of bridge structure on high speed railway line, it is necessary to consider comprehensively the common effect of the train, the track and the bridge. By forming an integrated large system including the car and locomotive system, track system, bridge structure system and making use the interaction of the wheel/rail as the ″link″ between these systems, the study focuses on the coupling dynamic analysis of the train, the track and the bridge. Based on the summary and digestion of the predecessor′s research experiences, this article studies the coupling vibration of the train, the track and the bridge structure system on the high speed railway line. It covers the following: 1. Establishment of a more completed dynamic analysis model for cars and locomotives: the four axle car with two level suspension is used for the study and a space vibration analysis model constituting of such rigid bodies as carbody, bogie frame and wheelset is built. There are totally 31 degree of freedom, i e, 5 for the carbody and the front and rear bogie respectively, including horizontal movement, bounce, roll, pitch and yaw, 4 for each wheelset, including horizontal movement, bounce, roll and yaw. In the wheelset movement equation, the previous assumption that the wheelset always keep rigid contact with track in the car bridge coupling analysis has been corrected. The wheelset is allowed to leave the track, i e, ″jump on rail″. The degree of freedom of the wheelset has increased from horizontal movement and yaw, 2 in total, to horizontal movement, bounce, roll, and yaw, 4 in total. The degree of freedom for the car model has increased from 23 to 31. 2.Establishment of track structure dynamic analysis model of the multi layer supporting system aiming at ballasted track bridge of multiple spans for the first time: in accordance with the type and characteristics of different track structure and their models and aiming at the most common used ballasted track, the study selected the continuous elastic Euler beam model with distributed parameters and the disperse point supports as the rail dynamic model. The rail sleeper bridge spring damping model is built for the track on the bridge and the rail sleeper roadbed spring damping model for the normal track. 3.Based on the wheel/rail vertical nonlinear elastic Herze contact theory and horizontal nonlinear creepage theory, the train(track(bridge dynamic analysis program has been worked out and used in test: According to the train(track(bridge dynamic analysis program introduced in this article, in the determination of the wheel/rail forces, the vertical interaction is treated by nonlinear elastic Hertz contact and wheel is allowed to jump on rail. The lateral interaction is treated first by the Kalker theory under the small creepage ratio conditions, the creepage force is considered as linear relations. Then the creepage force is corrected by Johnson Vermeulen nonlinear theory, making it applicable to the condition with large creepage ratio. It extends the calculation of creepage force extended to the large creepage ratio nonlinear condition from the previous small creepage ratio linear condition. Therefore, the calculation accuracy of the wheel/rail creepage force improved and the application conditions of the creepage force developed. In accordance with characteristics of the model built in this paper, the program, for the first time, adopts the cubic spline interpolation to derive the solution of the geometric spacial restriction of the wheel/rail with abitrary profile. In order to check the effectiveness of the program, the article takes the actual data from the home made train ″Shenzhou″ when it was passing the 158# bridge on the Jingqin line to validate the program. In accordance with the comparison and analysis of the actual measured data and the method used, the article notes the effect of the track structure in the computer model and increases the function of the dynamic analysis of the ″wheel jump on rail″ state. Therefore, in comparison展开更多
文摘The influences of the lateral motion of a single wheelset running on a tangent railway on the creepages and creep forces between wheel and rail are investigated with numerical methods. The effect of the yaw motion of wheelset is neglected in the analysis, and Kalker’s theory of three dimensional elastic bodies in rolling contact is employed to analyze the creep forces in the wheel/rail rolling contact with Non Hertzian form.
文摘Creep forces depend greatly on creepages in the contact area forming between wheel and rail.The creepages are completely determined by the state of a wheelset moving on a track.In this paper the contact state of a single rigid wheelset moving on a tangent rigid rail,creepages and their sensitivities to some parameters of contact geometry are analyzed by semi analytical method and numerical method,respectively.Some important ideas will be provided for the studies done on the interactions between wheels and rails at high speed.
基金supported by National Natural Science Foundation of China(Grant Nos.51175438,U1134202)National Science and Technology Support Program of China(Grant No.2009BAG12A01)Program for New Century Excellent Talents in University of China(Grant No.NCET-08-0824)
文摘Thermal damage caused by frictional heat of rolling-sliding contact is one of the most important failure forms of wheel and rail. Many studies of wheel-rail frictional heating have been devoted to the temperature field, but few literatures focus on wheel-rail thermal stress caused by frictional heating. However, the wheel-rail creepage is one of important influencing factors of the thermal stress In this paper, a thermo-mechanical coupling model of wheel-rail rolling-sliding contact is developed using thermo-elasto-plastic finite element method. The effect of the wheel-rail elastic creepage on the distribution of heat flux is investigated using the numerical model in which the temperature-dependent material properties are taken into consideration. The moving wheel-rail contact force and the frictional heating are used to simulate the wheel rolling on the rail. The effect of the creepage on the temperature rise, thermal strain, residual stress and residual strain under wheel-rail sliding-rolling contact are investigated. The investigation results show that the thermally affected zone exists mainly in a very thin layer of material near the rail contact surface during the rolling-sliding contact. Both the temperature and thermal strain of rail increase with increasing creepage. The residual stresses induced by the frictional heat in the surface layer of rail appear to be tensile. When the creepage is large, the frictional heat has a significant influence on the residual stresses and residual strains of rail. This paper develops a thermo-meehanical coupling model of wheel-rail rolling-sliding contact, and the obtained results can help to understand the mechanism of wheel/rail frictional thermal fatigue.
文摘Due to extensitve application of bridge structure on high speed railway line, it is necessary to consider comprehensively the common effect of the train, the track and the bridge. By forming an integrated large system including the car and locomotive system, track system, bridge structure system and making use the interaction of the wheel/rail as the ″link″ between these systems, the study focuses on the coupling dynamic analysis of the train, the track and the bridge. Based on the summary and digestion of the predecessor′s research experiences, this article studies the coupling vibration of the train, the track and the bridge structure system on the high speed railway line. It covers the following: 1. Establishment of a more completed dynamic analysis model for cars and locomotives: the four axle car with two level suspension is used for the study and a space vibration analysis model constituting of such rigid bodies as carbody, bogie frame and wheelset is built. There are totally 31 degree of freedom, i e, 5 for the carbody and the front and rear bogie respectively, including horizontal movement, bounce, roll, pitch and yaw, 4 for each wheelset, including horizontal movement, bounce, roll and yaw. In the wheelset movement equation, the previous assumption that the wheelset always keep rigid contact with track in the car bridge coupling analysis has been corrected. The wheelset is allowed to leave the track, i e, ″jump on rail″. The degree of freedom of the wheelset has increased from horizontal movement and yaw, 2 in total, to horizontal movement, bounce, roll, and yaw, 4 in total. The degree of freedom for the car model has increased from 23 to 31. 2.Establishment of track structure dynamic analysis model of the multi layer supporting system aiming at ballasted track bridge of multiple spans for the first time: in accordance with the type and characteristics of different track structure and their models and aiming at the most common used ballasted track, the study selected the continuous elastic Euler beam model with distributed parameters and the disperse point supports as the rail dynamic model. The rail sleeper bridge spring damping model is built for the track on the bridge and the rail sleeper roadbed spring damping model for the normal track. 3.Based on the wheel/rail vertical nonlinear elastic Herze contact theory and horizontal nonlinear creepage theory, the train(track(bridge dynamic analysis program has been worked out and used in test: According to the train(track(bridge dynamic analysis program introduced in this article, in the determination of the wheel/rail forces, the vertical interaction is treated by nonlinear elastic Hertz contact and wheel is allowed to jump on rail. The lateral interaction is treated first by the Kalker theory under the small creepage ratio conditions, the creepage force is considered as linear relations. Then the creepage force is corrected by Johnson Vermeulen nonlinear theory, making it applicable to the condition with large creepage ratio. It extends the calculation of creepage force extended to the large creepage ratio nonlinear condition from the previous small creepage ratio linear condition. Therefore, the calculation accuracy of the wheel/rail creepage force improved and the application conditions of the creepage force developed. In accordance with characteristics of the model built in this paper, the program, for the first time, adopts the cubic spline interpolation to derive the solution of the geometric spacial restriction of the wheel/rail with abitrary profile. In order to check the effectiveness of the program, the article takes the actual data from the home made train ″Shenzhou″ when it was passing the 158# bridge on the Jingqin line to validate the program. In accordance with the comparison and analysis of the actual measured data and the method used, the article notes the effect of the track structure in the computer model and increases the function of the dynamic analysis of the ″wheel jump on rail″ state. Therefore, in comparison
