Vehicle Dynamics Analysis In The Wheelsets Repair Cycle

With the continuous development of China's railway and the increase of train speed,the problem of tread wear is more prominent than ever.Wheel tread shape has a direct effect on the contact geometry relationship between wheel and rail,and has a significant influence on the safety and smoothness of high-speed train operation.Therefore,in this paper,the dynamic performance of the vehicle during the cycle of wheelsets repair is analyzed.This paper took the CRH5 high-speed EMU trailer as the research object.Based on the vehicle system dynamics theory,the vehicle dynamics model of train is established using dynamics simulation software SIMPACK.According to the numerical simulation method,the low interference spectrum of Germany is simulated by MATLAB software,and this is used as the line disturbance for the dynamics model established in this paper.In this paper,the tread shape of different operating mileage during the repair cycle is tracked and measured by specific equipment,and the measured data are transformed to a special file whose format can be identified by SIMPACK software.According to the operating mileage,seven treads of different wear degrees in the wheelsets repair cycle are selected as the treads S1 to S7,and then the geometrical contact relationship between the seven treads and the rails is analyzed by the wheel/rail relationship function of SIMPACK dynamics software.In this paper,the changing tread of dynamic index of different abrasion degree of the tread is analyzed by using seven different profiles,with 5 different running speeds ran through the straight line and three kind of curves respectively with radius of 800m,3000m and 7000m.The results show that the tread wear has a great influence on the nonlinear critical velocity,the derailment coefficient,the transverse force of the wheel and the rail on straight line,but the influence on the lateral stability,wheel load shedding rate,wheel and rail vertical force and the lateral stability is small.On the small radius curve,the change of dynamic index is not obvious with the increase of tread wear;With the increase of theradius of the curve,the dynamic performance index is more excellent;different ultra-high working conditions have a direct impact on the dynamic performance of the wheel.In this paper,the influence of the tread shape on the dynamic performance of the vehicle system under different wear degree in the wheel repair cycle is obtained by simulation analysis.The results of the research will have guiding significance on trains'tread repair limit,a provides a reference for the tread shape optimal design.