Analysis On High-Speed Braking Tribological Performance And Interface Vibration Character Of Train DISC And PAD

The brake disk and pad are basic components for ensuring the operation safety of high-speed train.The friction braking behaviors between the brake disk and pad has important significance for train safety operation.Therefore,the study of the friction and vibration behaviors of high-speed braking disk and pad has a great significance and application value for ensuring the reliability of high-speed braking system.A MM-1000 high-speed friction braking machine was used to carry the high-speed braking experiments.The effect of initial braking speed,braking pressure and water on high-speed friction braking interface behaviors were studied.MATLAB was used to transform the vibration signal to the time frequency map.The effect of water on frictional braking behaviors was explained by analyzing both the time frequency map and instantaneous friction coefficient curve.ABAQUS/Standard was used to calculate the temperature field of frictional braking interface using thermal-mechanical coupling method.Furthermore,the simulation result explains the evolvement rule of friction braking interface under different conditions.The main conclusions are as follows:(1)Under the dry condition,the average friction coefficient first increases and then decreases with the initial braking speed increasing.The average friction coefficient decreases with an increase in braking pressure.The fluctuation of instantaneous friction coefficient decreases with the braking pressure increasing.The instantaneous friction coefficient first decreases and then increases in the braking process.(2)Under low and medium initial braking speed conditions,the water has an obvious effect on the frictional braking behaviors.In the braking process,the instantaneous friction coefficient is low and the decrease of braking disk rotation speed is non-linear.With the initial braking speed,braking pressure and temperature increasing and the water flow decreasing,the water on the friction braking interface obviously decreases.The interface condition is similar with the dry condition.Therefore,the effect of water on frictional braking behaviors is significantly weakened.The water sealed up in the cracks leads to partial high pressure point on the friction surface,which results in serious pitting damage on the braking disk and pad.(3)The resample of original vibration signal can reduce the amount of calculation and has no obvious influence on the time frequency analysis of low frequency signal.In the time frequency map disposed by Morlet wavelet transformation,the slope of vibration frequency indicates the variation of the rotation speed of disk.(4)The temperature of friction braking interface first rises and then drops in the frictional braking process,which causes the instantaneous friction coefficient to first decreases and then slightly increase.The highest temperature appears around the average friction radius of braking disc and pad in the 15?25%braking process.The temperature on the left area of pad is higher than that on the right area,which leads to the partial wear on the left area of pad.