| With the rapid development of China’s national economy,the transit time between cities has been continuously shortened.Compared with the conventional highway,high-speed railways are characterized with low energy consumption and low pollution.In comparison to ordinary railways,high-speed railways feature fast running speed,relatively smooth operation lines,and large radius of curves required for running lines,which make the high-speed EMUs in operation have special wheel-rail geometric relations.In order to meet the diversified and long-distance transportation needs of high-speed railways,the high-speed EMUs in service must undergo continuous operation for a long time.During the operation,wheel wear gradually becomes more prominent as the operating mileage increases,and the wheel-rail geometric relations of wheel wear will affect the vibration characteristics of the vehicle system which will reduce the EMU’s operational stability and ride comfort.Therefore,it is of great significance to study the effect of wheel wear of high-speed EMUs on the vibration characteristics of the vehicle system,and it can also provide a theoretical basis for the re-profile cycle for high-speed EMUs.This paper,taking a certain type of CRH EMU as the research object,selected a relatively complete Line C in the test process to conduct on-site research on the EMUs based on the long-term tracking of the EMU through the method of collecting the data of wheel wear and vehicle vibration on a regular basis.Based on the actual test conditions,the evolution of wheel tread wear and rim wear for EMUs was studied under different mileages.By employing the Sperling Assessment Index of running stability for passenger trains,the test vehicle’s running stability,the evolution of the vehicle’s stationarity,and the vibration transmission status of the vehicle are studied as the operating mileage increases.In addition,this paper built a vehicle dynamics model based on UM.By inputting the track irregularity of the test line and the curve radius of the running line and inputting the measured tread wear into the model to carry out simulation,the simulation data would be acquired.Combined with the measured data and simulation data,this paper studied the smoothness,stability,wheel load reduction rate and derailment coefficient of the vehicle at 350 km/h and analyzed the evolution with wheel wear.According to the combination of test data and simulation data,this paper proposed re-profile cycle of EMU running on Line C and simulated and verified the re-profile cycle.The research results show that wheel tread wear increases with the increase of operating mileage,and wheel flange wear process features an increasing rate.The lateral acceleration of the frame and the lateral stability of the vehicle body are proportional to the running mileage,and the vertical stability of the body does not change greatly with the mileage.In addition,the main frequency of the frame lateral acceleration on the C line is 40Hz~50Hz,and the main frequency of the vertical vibration acceleration of the vehicle body is 2Hz~5Hz,28Hz~31Hz.The transmission ratio of the axle box-framework is about 0.47,and the transmission rate of the frame-car body is about 0.04.A series of shock absorbers play a major role in damping the vehicle.Based on simulation result,after the equivalent taper running mileage of wheel exceeds 338,000 kilometers,exceeding relevant prescribed value of 0.35 g,it is recommended that the EMU train wheel re-profile cycle should be between 310,000 kilometers and 330,000 kilometers.This paper studied the vehicle vibration status of EMU under different operating mileage and provided reference for re-profile cycle of the EMU on the test line based on software simulation. |
