Study On The Subway Wheel Wear And Influence On Dynamic Performance

With the increase of subway passenger flow and departure frequency,the problem of subway wheel wear is becoming more and more serious.The influence factors and prediction of wheel wear are of great significance to reduce wheel/rail wear and the cost of turning.According to the characteristics of real-time passenger flow change,frequent starting and braking,and high curve proportion of metro vehicles,this paper takes metro wheels as the research object,combined with the measured passenger flow,wear and dynamic data,analyzes the influence of five factors on metro wheel wear: time-varying load,time-varying speed,dynamic wheel profile,friction coefficient and wear coefficient.Firstly,according to the time-varying load caused by the dynamic change of passenger flow and the speed change caused by vehicle traction and braking,a simulation model of metro wheel wear is established based on the condition of variable load and variable speed.Then,in view of the dynamic change of wheel profile with running mileage,the evaluation method of wheel/rail friction coefficient based on dynamic wheel profile is put forward,considering the wheel/rail wear performance and vehicle curve passing capacity.On the basis of time-varying load,time-varying speed,wheel profile and friction coefficient,the wear coefficient is optimized by using the measured wear data of specific mileage,and the wear prediction model of metro wheel based on integrated data-model-driven approach is established and verified by the measured value.Finally,based on the measured data of wheel wear and out-of-round(OOR),the influence of asymmetric factors and coupling factors of wheel damage on the dynamic performance of metro vehicles is further studied,and the coupling damage dynamic model of asymmetric OOR and tread wear of metro wheels is established.The main achievements and conclusions are as follows:(1)According to the characteristics of the real-time change of the passenger flow of metro vehicles,a time-varying load calculation method based on the dynamic passenger flow is proposed;according to the characteristics of the frequent start-up and braking of metro vehicles,a time-varying speed function with the change of time and position is established,and a simulation model of the wheel wear of metro based on the change of load and change of speed is constructed.Through the combination of vehicle dynamics model,variable load setting model,variable speed setting model,wheel/rail contact model,material wear model and tread renewal model,the simulation results of wheel wear under dead load and variable load are calculated and analyzed,and compared with the measured wear data.The results show that,compared with the dead load condition,the calculation results of wheel wear under the variable load condition are closer to the measured wheel wear data,and with the increase of running mileage,the calculation advantages of the variable load and speed change model are more and more obvious,and the calculation results are consistent with the measured values.Therefore,the prediction accuracy of the simulation model of subway wheel wear based on variable load and variable speed conditions,which considers the factors of passenger flow change and speed change,has been greatly improved,providing a more accurate basis for the simulation prediction and lathing of wheel wear.(2)In view of the dynamic change of wheel profile with running mileage,the evaluation method of wheel/rail friction coefficient based on dynamic wheel profile is put forward considering the wheel/rail wear performance and vehicle curve passing capacity.The S-shaped curve is used to simulate the actual running section of an interval station,and the wear index and derailment coefficient are taken as evaluation indexes.Through the system dynamics model and wear model of metro vehicles,the influence rules of four kinds of measured wheel wear profiles and seven different friction coefficient values on the wear index and derailment coefficient are calculated and analyzed,and the optimal friction coefficient values of different wheel wear profiles are obtained.The results show that the best friction coefficient range of standard wheel profile is 0.1-0.15,the best friction coefficient range of 50000,80000,140000 km wheel profile is 0.1-0.2,0.1-0.2,0.1-0.15;by adjusting the friction coefficient with wheel/rail lubrication technology,the maximum wear index of 0,50000,80000,140000 km wheel profile can be reduced by 71%,73%,69%,56% respectively.Therefore,the friction coefficient evaluation from the point of view of wheel dynamic profile under different running mileage can effectively reduce wheel/rail wear and provide technical support for wheel/rail friction control of metro curve line.(3)The optimization method of wear coefficient based on the measured data is proposed,and the wear prediction model based on based on integrated data-model-driven approach is constructed.The wear coefficient of Jendel wear model is optimized by using Genetic Algorithm,Particle Swarm Optimization,Simulated Annealing and Tabu Search.The calculation results of the four algorithms are compared under different routes and running mileage.Considering the optimization accuracy and calculation time,Particle Swarm Optimization is the best.On the basis of the optimization of wear coefficient,the prediction model of the wheel wear based on integrated data-model-driven approach is constructed.The simulation and prediction of the wheel wear of metro under other operating mileage are carried out,and the comparison with the measured data is made.The research results show that the optimization method of wear coefficient based on the measured data can effectively reduce the uncertainty of selecting wear coefficient by experience and reduce the cost of experimental data;the subway wheel wear prediction model based on integrated data-model-driven approach combines the advantages of model prediction and data prediction,improves the accuracy of wheel wear prediction,and provides a new kind of wheel wear simulation prediction ways.(4)In view of the unsymmetrical damage and coupling damage of wheels in the actual line,combined with the measured wear and out-of-round(OOR)damage data of Metro wheels,a dynamic analysis method based on the unsymmetrical damage and the coupling damage of wheels is proposed.The dynamic model of the coupling damage of the unsymmetrical OOR and wear of the metro wheel is established,and the influence of the unsymmetrical damage and the coupling damage on the dynamic performance of the vehicle system is studied.The calculation results of vehicle dynamic performance of unsymmetrical OOR and symmetric OOR,uncoupled and coupled damage,unsymmetrical and symmetric coupled damage are analyzed and compared with the measured results.The results show that the wheel/rail vertical force,derailment coefficient and wheel load reduction rate of asymmetric OOR condition increase obviously;in the coupling damage,the change of wear has a great influence on the wheel/rail lateral force,wheel axle lateral force and derailment coefficient,but has a little influence on the wheel/rail vertical force;compared with symmetrical coupling damage condition,the peak value of vertical vibration acceleration and stability index of asymmetrical coupling damage are more close to the measured data.Therefore,the dynamic model of the coupling damage of the unsymmetrical OOR and wear,which is based on the consideration of the unsymmetrical factors and the coupling damage factors,is helpful to the accuracy of the calculation results and has reference significance for the maintenance and repair of the metro wheel.