Study On Dynamic Performance And Wheel Wear Of High Speed Motor Cars

With the development of CRH high speed EMUs,the train running speed and carrying capacity have been improved,Chinese railways have entered into the faster developing stage.The operation range,line condition and climatic enviroment of the EMUs are diversified.The EMUs bring people safe,comfort and convenient travel.But meanwhile,there exists different dynamic issues in the long service period.Therefore,the study on line operation adaptability of high-speed train has been paid more and more attention by researchers home and abroad.From the viewpoint of dynamics and aimed at the line operation adaptability,this thesis studies the system vibration,dynamic performance and the evolution rule of wheel profile wear during the service of high speed train,and analyzes the fundamental problems of the line adaptability by the combination of simulation and experiment.This thesis is funded by the key project of National Natural Science Foundation of China,"Key Issues of Safety Performance Assessment of High Speed Trains in Service Based on Monitoring Data"(61134002).The following aspects are extensively studied in the thesis:(1)In order to study the influence of wheel-rail profile wear on vehicle vibration performance and running quality,this thesis describes the modeling method of nonlinear high speed motor car system with considering the driving system,and establishes the multi-body dynamic model and suspension parameter failure model.Meanwhile,the dynamic model is verified using the roller rig test.The results show that the modal parameters of the body and frames are relatively close for this two items,the suspension system faults have the greatest influence on the stability,followed by anti-hunting shock absorber,and the test data and simulation data are relatively close in both numerical value and trend.In order to study the key problem of wheel profile wear,the model of wheel profile wear prediction is established.(2)The field tracking test scheme is given,and the long term tracking test is carried out.Then,the evolution of vehicle vibration performance and ride comfort under different operating mileage is analysed.And also the changing of wheel profile wear and equivalent conicity of the vehicle is investigated in a re-profiling period.The results show that the amplitude of motor vibration acceleration tends to decrease with operating mileage,and the line factors have a great influence on the transverse vibration of motor vibration.Line factors and running mileage have a great influence on the lateral and vertical vibration of the gearbox.The relationship between the frame and the transverse vibration operation line of the car body is large.According to the change law of transmission rate and transmission main frequency,the motor car is not sensitive to snake movement.The wearing area is relatively concentrated and the wear at the wheel flange root is very small.Wear range is not sensitive to running mileage;The wear rate changes nonlinearly with the increase of operating mileage.Based on the evolution of wheel profile wear,the rationality of the wheel profile wear prediction model is verified by experiments.(3)Based on the dynamic model,the effect of wheel profile on vehicle stability,ride comfort and curving performance is analyzed.The dynamic response of various parts of the vehicle is studied.The influence of the operating mileage and the wheel/rail wear profiles on the dynamic performance of the motor car is investigated.The dynamic performance changing under the suspension parameters failure in the wheel/rail wear condition is calculated by numerical simulation.The influence of the motor suspension stiffness on the acceleration of the motor and the deformation of the suspension is discussed.The influence of the cardan shaft diameter on the acceleration of the motor and cardan shaft and the deformation of the suspension is also discussed.The results show that dynamic performance is sensitive to line conditions and wheel profile.The failure modes of suspension parameters have different influence on dynamic performance.When the suspension stiffness of the motor increasing will result in increased the vertical acceleration of the motor and decreased the deformation of the spring.When the diameter of the universal shaft is increased,the vertical acceleration of the universal shaft becomes smaller,the vertical acceleration of the motor becomes larger,and the amount of spring expansion decreases first and then increases.(4)This thesis gives a detailed description for wheel profile re-profiling strategy and the economic re-profiling template design,and analyzes the equivalent conicity and dynamic performance for the designed economic re-profiling template.The results show that the template meets the requirements for safe operation of the vehicle.The wheel wear increases slightly with the decrease of flange thickness,and the wear in the tread area is close.(5)The key factors affecting wheel profile wear is studied.Based on the vehicle dynamics model and the model of wheel profile wear prediction,from the viewpoint of the wear volume and the wear depth,the influence of the vehicle system parameters(axle load,the stiffness of primary suspension,lateral stiffness of the air spring,bogie wheelbase,wheel hardness,wheel profile,wheel diameter,wheelset initial assembly error and radius difference),track system parameters(curve radius,rail cant,gauge and rail profile),operating conditions(running speed,track excitation,wheel/rail contact surface condition)and economic re-profiling are analyzed on the wheel profile wear.The results show that although the wear degree of the initial profile of the wear prediction model is different,the same key parameters have the same influence on the wear,such as axle load,wheel hardness,wheelset initial assembly error,radius difference,curve radius,gauge,friction coefficient,track excitation,and some parameters have changed,such as the stiffness of primary suspension,the lateral stiffness of the air spring,bogie wheelbase,wheel diameter,rail cant,rail profile wear,and running speed.Therefore,the influence of wheel-rail wear cannot be ignored in the parameter design of high-speed motor cars.