Study On Wheelset Wear Of Heavy Haul Railway Freight Cars And Its Influence On Dynamics

With the great development of the national economy and the continuous improvement of economic activity,in the foreseeable future,railway freight will be busier and busier,and the transportation task will be heavier and heavier.Therefore,it is necessary to keep up with the development of the times in the research and maintenance of freight car related technologies.Not only the safety of railway freight car transportation is the top priority,but also it is essential to reduce the operation and maintenance costs and improve the economic benefits on the premise of ensuring the safety of train operation.This paper mainly studies the wear law of freight car wheelset and its influence on dynamic performance,which provides a certain reference for engineering practice.Firstly,by analyzing the physical simplified model of the railway freight car,grasping its stress condition,and dealing with the nonlinear relationship,the vehicle system dynamic model is constructed by using SIMPACK,which provides the calculation of dynamic parameters for the joint simulation model of wheelset wear.In this paper,based on the space trace method,the calculation program of wheel-rail contact point pair is established;based on the in-depth study of contact theory,the programs based on Hertz contact theory and non-Hertz contact theory are established respectively.The size and shape of the wheel-rail contact spot,the internal stress of the contact spot,and the distribution of the stick-slip zone can be calculated by given parameters.Compared with the shape of the contact spot observed in the experiment,the non-Hertz contact spot based on the virtual penetration method is closer to reality.Secondly,based on the wheelset wear detection data influenced by many factors,the decoupling analysis method of characteristic parameters related to wheel wear is proposed:the range of any two parameters of wheel diameter difference,wheel diameter value,and flange thickness that affect the wear are controlled,and the influence law of the third factor on wheel wear is analyzed.When analyzing the wheel profile data,the standard LM profile program and the measured profile matching analysis program are established to calculate the wear amount of each position of the measured profile;for the tread wear analysis,this paper puts forward a method to evaluate the tread wear state based on the maximum wear point and the left and right wear points.According to the preliminary analysis data,the data points with large deviations are eliminated by the triple normal distribution,and the relatively reliable wear law is obtained by the fitting.Finally,based on the established dynamic course model of the vehicle system and the related program of wheel-rail contact,the co-simulation model of SIMPACK and MATLAB is constructed,and the wheel tread wear under corresponding working conditions is analyzed.Based on the co-simulation model,the relationship between wheelset wear law and flange thickness of standard wheel and different combinations of flange thickness is studied,and the influence of four typical wheel diameter differences and wheel diameter differences on wheelset wear is analyzed.According to the influence law of flange thickness,wheel diameter difference on wheel wear obtained from the analysis,the influence law of standard tread flange thickness,wheel diameter difference,and worn rear wheel on vehicle system dynamics is discussed.The results show that: the influence of flange thickness and wheel diameter difference on wheel wear is much greater than that of wheel diameter,and with the increase of the absolute value of flange thickness and wheel diameter difference,the wear basically increases,but the influence of small-diameter wheel is greater;when there is only the same frame wheel diameter difference,it is found that there is little change in wheel wear with the change of same frame wheel diameter difference;the change of flange thickness under the condition of standard vehicle profile wheelset It has little effect on the dynamic performance,but the dynamic performance becomes worse with the increase of wheel diameter difference;the dynamic performance of the worn wheelset changes greatly compared with the standard profile wheelset,and even exceeds the limit when the speed reaches a certain value.