Influence of friction self-excitation of brake pair on wheel wear of rail vehicle
Periodic wheel-rail wear will intensify the dynamic wheel-rail interaction,resulting in fatigue fracture of key components of the vehicle system and abnormal vibration of the vehicle body,which has a great impact on ride comfort and operation safety.However,previous studies rarely link brake pair vibration with wheel wear.In order to study the causes of periodic wheel wear,in this paper,the effect of self-excited oscillation of brake unit on wheel wear was considered for the first time.Firstly,the torsion model of the train braking system considering wheal-rail attachment was established.The vibration state of the braking system was solved by numerical method.The vibration of the system under braking conditions was deeply explored through some nonlinear correlation graphs(bifurcation diagram,phase diagram,Poincare cross section diagram,spectrum diagram and time domain diagram of the system motion,etc.).The influence of self-excited oscillation on wheel wear caused by negative slope of friction coefficient in brake unit was obtained.The results show that the unstable motion caused by friction self-excitation of the braking system only occurs at low speed.With the decrease of the braking speed,when the speed is lower than 12.88 km/h,the braking system will enter the oscillation range from the stable range,which will cause the braking system to flutter.At the same time,the flutter of the braking system will cause the fluctuation of wheel creep rate,which will affect the tangential force and wheel-rail wear.When the braking speed is in the oscillation range,the wheel will appear uneven wear.When the braking speed is close to the critical value of the oscillation interval,the wheel wear is approximately uniform.When the braking speed is in the stable range,the longitudinal creep force of the wheel does not fluctuate,and the wheel no longer has abnormal wear due to the self-excited oscillation of the brake pair.The influence of braking pressure on the system motion stability and wheel-rail wear is investigated.It is found that the amplitude of the system increases and the wear becomes more obvious under large braking pressure.Exploring the influence of brake system on the periodic wear of vehicle can provide reference for the study of the mechanism of periodic wear of wheel and the selection of control measures.
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