Research On Transient Wheel-Rail Fricitional Rolling Contact Behavior And Non-Uniform Wear In Turnout Switch Panel

The high-speed vehicle is supported and guided by the wheel-rail frictional rolling contact and the traction/braking force caused by self-adhesive effect.Especially affected by the structural irregularities and multi-point contact in the turnout,the coupling effect of rolling and vibration exists in the continuous and complex process of high speed rolling,high frequency vibration,curve motion and passing turnout,therefore the wheel-rail frictional rolling contact behavior will not only affect the running comfort and stability of the vehicle,but also may lead to failure of traction or braking,thus threatening the running safety of the vehicle.Based on the existing research of well-known scholars domestic and overseas,the wheel-rail frictional rolling contact behavior and non-uniform wear distribution in turnout switch panel is studied.The main research contents include:1.Transient wheel-rail frictional rolling contact behavior in switch panelThe explicit finite element model of switch panel in turnout is established based on the explicit integral algorithm,which can consider the coupling effect of structural vibration and contact mechanics,arbitrary contact geometry and material nonlinearity.Furthermore,the wheel-load transition and wheel-rail impact caused by the variable cross-section characteristics of switch rail are simulated,and the transient and drastic changes of size,stress and microslip in contact patch between wheel and switch rail are studied in detail,the instantaneous distribution of wheel-rail mesoscopic contact information and the high frequency vibration characteristics of rail under short time(0.0004s)are analyzed.Then the accuracy of the simulation model is verified based on the field measured data of the lateral displacement of wheelset and the stress distribution during transition.2.Non-uniform wear prediction in switch panelBased on the analysis process of wear prediction in switch panel,the non-uniform wear prediction method on stock rail and switch rail is established.First,the precise magnitude and distribution of stress and strain in contact patch can be obtained from the wheel-rail explicit finite element model,then Combined with the Archard's wear model,the profile evolution and smoothing method,profile iteration method and wear accumulation method,the wear prediction method considering the profile evolution can be established,therefore the relationship between profile evolution due to the number of passing times caused by wear and wheel-rail contact behavior can be considered.The method takes into account the coupling effect of wheel-rail contact information and macroscopic wheel-rail dynamic response which cannot be considered in the traditional method(combination of MBD and wheel-rail contact theory),therefore the more accurate results can be obtained.3.Key affecting factors analysis of wear and wheel-rail contact in switch panelAccording to the investigation of the wheel-rail transient frictional rolling contact behavior,the vehicle-switch dynamic parameters which have a significant effect on the wheel-rail frictional rolling contact behavior and non-uniform wear distribution of the rail are studied.Then combined with the explicit wheel-rail dynamic analysis theory,unreplicated saturated factorial design method,wheel-rail prediction theory and statistical processing method,the effect evaluation indexes of the analysis factors are calculated.The factors which have great influence on the wheel-rail transient rolling contact behavior and wear are figured out through graphic analysis method,on this basis,the influence of key affecting factors on the wheel-rail transient rolling contact behavior and wear is analyzed,the simulated results mainly includes the contact stress,shear stress and microslip in contact patch.4.Simulation analysis of wheel-rail contact behavior and rail wear in switch zone under traction/braking forceTo recognize the influence of the traction force on the wheel-rail contact behavior and non-uniform distribution of wear in turnout,the comprehensive explicit finite element method,profile updating method and Archard's wear model are integrated as a method for evaluating the performance of the turnout,where the coupling relationship between local contact behavior and structural dynamics,actual motion status of wheelset and precise contact solutions due to frictional rolling contact are considered,three conditions of different traction coefficient are employed to investigate the transient contact solutions,precise stress/strain analysis and uniform distributed wear in turnout.To verify the accuracy of the simulation model,the long-term wear tracking test in turnout is conducted,the measured and simulated data of turnout rail wear are in good agreement.5.Research to reduce wear of switch panel rail based on explicit integration algorithmTo reduce the development of wear on rail,the influence of laminar plasma quenching method and optimation of value reduced for switch rail on wheel-rail rolling contact behavior and non-uniform wear is studied.In terms of value reduced for switch rail,the influence of different value reduced for switch rail on the wheel-rail rolling contact behavior and non-uniform wear is studied.In terms of laminar plasma quenching method,the explicit finite element model is developed for precise contact solutions after selective quenching.This takes cyclic loading and rail profile evolution into account,with the nonlinear material model used for cyclic quenching and ratcheting effect.Then the simulation results combined with the fatigue model is developed for the crack initiation life after quenching.Based on this,the most critically susceptible position to crack and number of cycles are predicted,and the simulated results are verified through comparison with quenching rail in service.