Influence Of EMU Wheel Profile Evolution On Vehicle Dynamics

When the train runs on the line,the wheel-rail contact surface inevitably wears out.The evolution of the tread shape of the wheel changes the geometric relationship between the wheel and rail contact,which affects the dynamic performance of the train.Therefore,the application department needs to regularly check the wheel alignment.For repairs,it is even better to change the wheel pair(equivalent to individual repairs)and the degree of repair in advance.Therefore,it is important to study the wheel pair after wear for vehicle dynamics and wheelset scientific maintenance.In this paper,the wheel wear tracking measurement data is used to select the 5 sets of data of No.1(first car),No.4 and No.7 cars from a repair cycle in which a part of the wheel pair is replaced,and the wheel wear evolution is analyzed by vehicle dynamics calculation.The impact of vehicle dynamics performance.The analysis results show that the wheel wear evolution makes the wheel/rai1 contact point distribution uneven and lateral jump(Maximum span of 24 mm),wheelset rolling radius difference and wheelset equivalent conicity increase,resulting in a decline in the critical speed of the vehicle,and the final maximum reduction is about 35%.At the same time,the wheel/rail force,vibration acceleration and other indicators become larger,which makes the vehicle vibration amplitude increase and the vehicle dynamic performance deteriorates.When the mileage is about 267,795 kilometers,the maximum wheel tread wear is about 1.87 mm.The critical speed of the No.1 car dropped to about 235 km/h,the Sperling Stable Index of each car exceeds 2.5,which poses a safety hazard to some extent.For the No.4 car,after running about 135,264 kilometers,the wear of the No.2 wheelset reached about 1.31 mm,the critical speed dropped to 296 km/h,and the vehicle Sperling stability index was as high as 2.76.After about 152,101 km,the No.2 and 3 wheelset were replaced,and the critical speed was increased to about 358 km/h.The corresponding linear running performance was improved to different extents.However,when passing the curve,the wheel-to-wheel traverse amount is increased due to the decrease of the radius difference of the wheel-to-roll circle,and the rim contact is formed,and the lateral force of the wheel-rail is increased by about 1.7 times.Although the vehicle's dynamic performance decreased rapidly due to the rapid wear of the wheels at the beginning of the wheel change,all the indicators met the requirements.Therefore,on the one hand,in the case of serious wear of individual wheelsets,the wheelsets are replaced as appropriate to ensure dynamic performance and maintenance cost,which is reasonable to a certain extent.On the other hand,the trend of deterioration of vehicle dynamics performance has not changed,leading to the early re-profile of the entire train.In summary,the evolution of the wheel profile due to wear has a greater impact on vehicle dynamics.