| Wheel-rail system,as the key system of train operation,plays an important role in the reliability,quality and comfort of train.The problem of wheel and rail friction and wear has also been concerned by researchers at home and abroad.Wheel slippage occurs when the train travels on a large ramp or starts.When the wheel skids,it will cause serious scratches and even deformation to the wheel and rail.Further research on the wear problem of wheel and rail sliding is of great significance to improve the wear resistance of wheel and rail materials and to understand the stress state between wheel and rail during slipping.In this study,sliding friction and wear experiments of wheel-rail specimens were carried out,and the effects of experimental parameters on friction and wear were analyzed.A three-dimensional finite element model of wheel-rail contact was established in ABAQUS software to analyze the variation of stress state and wear between wheel and rail when the simulation parameters are applied to wheel-rail sliding.The main research work is as follows:(1)Aiming at the slippage of the wheels during the running of the train.Based on MRH-5 high-speed friction tester,the sliding friction and wear experiments of ER8 and CL60 wheel materials and U71Mn rail were carried out.The sliding friction and wear tests of wheel-rail specimens under dry friction,water and water-sediment mixtures,different pressures and rotational speeds were carried out.Prepare for the analysis of friction coefficient,temperature,wear trace profile,wear and wear morphology.(2)According to the experiment results of ring-block sliding friction and wear,the changes of friction coefficient,temperature,wear trace profile,wear and wear morphology were analyzed,and the effects of different friction media(dry friction,water and sediment mixture),pressure and rotational speed on sliding friction and wear test were obtained.According to the wear obtained from the experiment,the Archard wear model was improved and the wear model suitable for the experiment conditions was obtained.It is found that the experimental parameters have a significant effect on the friction and wear properties,and the error between the analytical results and the experimental results is about 5.74%.(3)Based on ABAQUS,a three-dimensional finite element model of wheel-rail sliding contact is established with 1/8 wheel and rail as the analysis object,and the mesh of contact area is refined.The static contact of the model is verified by Hertz contact theory.The Mises stress,shear stress,contact pressure and contact spot between wheels and rails are analyzed under the parameters of friction coefficient,axle weight and sliding speed.Variations of stress between wheel and rail under different friction coefficient,axle weight and sliding speed are obtained.Based on the improved Archard wear model,the variation of rail wear under different axle weights and sliding velocities was obtained.The results show that the simulation parameters have a significant impact on the stress state between wheel and rail,and the increase of axle weight and sliding speed will aggravate rail wear.Based on the above work,the rule of friction and wear change during wheel-rail sliding can provide theoretical guidance for improving wear resistance of wheel-rail material.It provides a reference for further exploring the causes of wheel-rail scratches and cracks during sliding and prolonging the service life of wheel-rail. |
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