| The leap in time and space of high-speed trains,the service status and safety status between the wheels and rails are always in the process of dynamic change.The rolling contact between the wheels and rails will inevitably lead to the occurrence of wheel-rail wear due to friction,and the wheel wear will cause the lateral and circumferential geometric deformation of the wheel tread,and material properties such as surface roughness and surface hardness on the contact interface also change.Based on this,a wheel-rail rolling contact model considering wear-induced wheel surface state changes is established and related research is carried out,which has practical application value to provide theoretical support and technical guidance for the maintenance of high-speed train wheel-rail system.In this paper,the state of the left and right wheel treads of the same wheelset of the motor vehicle under the CRH380 full-life operating mileage is tracked and measured.Based on the on-site tracking test,mathematical statistical analysis and other means,the surface roughness tester,hardness tester,and LB wheels shape dimension detection system are used to complete the tracking test of the lateral geometric profile,lateral roughness and hardness of the wheel tread under the high-speed train service state,and test the circumferential out-of-roundness of the wheel and the corresponding changes in the circumferential hardness and roughness at the same time,establish a database of wheel surface roughness and surface hardness,and analyze the evolution of wheel tread geometry,wheel out-of-roundness,surface roughness and surface hardness with the service mileage of high-speed trains through data processing.Then,based on the measured surface characteristics of the wheel in service state,the 3D optical profiler is used to obtain the contour data of the wheel surface.Combined with the fractal theory and the finite element method,considering the change of surface roughness and surface hardness under the wheel wear state,the wheel-rail rolling contact model is established.The nonlinear spring-damping function contact model is used to define the wheel-rail rolling contact relationship.Combined with elastic-plastic mechanics,contact mechanics and energy damping dissipation theory,the dynamic normal contact characteristics between wheel and rail in service state are studied,and further analyze of the influence of high-speed train axle load,hardness,lateral movement and running speed on the normal contact stiffness-damping between wheel and rail.Finally,the GPM-30 rolling contact testing machine is used to carry out rolling friction experiments of wheel-rail samples under different working conditions to obtain the surface characteristics of the samples and study the tangential friction characteristics.On the one hand,using the control variable method,the test factors are divided into three factors,such as the test load,the creep rate and the test speed,and group experiments are carried out respectively to study the influence of different working conditions on the tangential friction characteristics of wheel-rail samples.On the other hand,by carrying out experiments under typical working conditions,discrete experimental data of friction coefficient,surface roughness and surface hardness changes under different working conditions are obtained.A functional friction model related to the surface state is established,and the surface state and friction coefficient of the wheel-rail samples under different typical working conditions are compared and analyzed. |
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