Research On The Influence Of High Speed Train Dynamic Characteristics On Wheel Tread Wear

With the increasing mileage of high-speed train in China,high-speed train has become the main way for passengers to transport.With the continuous increase of passenger capacity and operation speed,the vehicle dynamic problems caused by the wear of wheel and rail are increasing,which also affects the economics of high-speed railway operation.At present,the problems caused by wheel and rail wear mainly include abnormal carbody vibration,the lateral acceleration of bogie excessived limit value,ride index and safety index decrease,fatigue damage of running parts.Therefore,it is necessary to further study the wheel wear of high-speed trains.The problem is to ensure the safe operation of the train and good dynamic performance.In this thesis,a high speed trian track coupled dynamic model is established,a Jendel wheel wear model based on hardness modified was proposed,and the wheel wear prediction program was written.The effect of the wheelset elasticity,the drive system,the variable stiffness and temperature-varying characteristics of rotary arm positioning nodal points,and hunting state on the wheel wear was investigated.Based on the establishment of high speed trian and track coupled dynamic model and the hardness modified Jendel wheel wear model,the calculation program of high-speed train wheel wear was written,in which both the curved track and straight track can be considered.The Jendel model and modified model were used to predict the wheel wear of CRH3 EMU,respectively,and the wear results were compared with the measured ones.The comparison results showed that under 50000 km operation mileage,the modified model is more accurate,the wheel wear depth error is less than 4%,and more suitable for predicting the wheel wear of high speed trains in China,which verifies the reliability of the model.The influence of wheelset elasticity on wheel wear was studied.The rigid-flexible coupled dynamic model of the wheelset was established,and more accurate wheel rail contact parameters were used to reflect the actual wear state of the wheel tread.By calculating the wheel rail contact parameters considering the elastic deformation of the wheelset,it can be found that the wear calculation accuracy can be guaranteed when the first three modes of the wheelset are considered.And the effects of vehicle parameters and track parameters on wheel wear were studied.The model of the drive system of vehicle dynamics was established.The traction torque characteristics and the track random irregularity excitation were considered in this model.The results were verified by the line test data.The variation of wheel rail contact parameters under traction and braking conditions is obtained through the calculation of the wheel rail contact dynamic parameters.The vehicle dynamics model considering the drive system can more realistically simulate the dynamic response of the high-speed train in actual operation.Traction motor harmonic torque is a nonnegligible excitation source for high-speed train operation.The wear parameters and wear depth of high-speed train under straight and curved track were calculated.The simulation results showed that the harmonic torque has a great influence on the normal force and longitudinal creep force of the wheel and rail,and has little effect on the lateral creep force.When the 30% harmonic torque works,the wheel rail normal force,the longitudinal creep force and the lateral creep force increase by 7.6%,15% and 4%,respectively.An increase in the harmonic content of the motor can accelerate wheel wear,while a small longitudinal positioning stiffness helps to mitigate the effects of harmonic torque.The variable stiffness model of the rotary arm positioning nodal points was established and its frequency-varying and amplitude-varying characteristics were analyzed.The effect on the variable stiffness fo the rotary arm positioning nodal points on the vehicle dynamics performance and wheel wear performance was analyzed.The wheel wear depth obtained by the variable stiffness model under straight track and curved track decreases co MPared with the fixed stiffness model.As the radius of the curve increases,the effect of the variable stiffness model is weakened.The temperature has a great influence on the stiffness and damping of the rotary arm positioning nodal points.When the measured joint stiffness and damping value are used,the wheel rail contact characteristics and wheel wear are significantly different at-30 °C because the creep force and contact patch were different.This thesis analyzed the reasons for the high speed train's cross-line shaking problem.The phenomenon of high speed train cross line shaking was simulated.When the high speed train crosses the line,the equivalent conicity increases,the wheel rail contact is mainly close to the root of wheel flange,and the wheel rail contact relationship deteriorates.This is the main reason for the high frequency shaking of the high speed train.The contact characteristics of wheel and rail under the condition of first and second huntings were analyzed by simulation,and the wheel wear under different line conditions was calculated.When the vehicle was in the state of first hunting,the contact angle,wheel rail creep force and contact patch area will fluctuate periodically under the condition of hunting,and the wheel wear will increase.The wheel wear under 200000 km wear mileage were predicted in two hunting states.It is found that the maximum wear depth is about 1 mm after the first hunting state and 0.58 mm after the second hunting state.