Research On Vibration Fatigue Of Sanding Device Of EMU

As an accessory part of the bogie,the sanding device plays an important role in improving the adhesion of wheel-rail interface to prevent the wheels from sliding.Since the sanding device is mounted on the axle box,it is directly exposed to high frequency vibrations from the wheel rail.In high-speed conditions,this high-frequency vibration becomes more pronounced,resulting in a series of structural failures,which seriously threaten the operational safety of EMU.Therefore,in this thesis,combined with the vehicle system dynamics and rigid-flexible coupling theory,a random vibration model of the sanding device that can reflect the vibration level of the axle box is established by using the pseudo-excitation method.Based on the measurement,the vibration spectrum of sanding device was defined.The difference between the measured vibration spectrum and the standard vibration spectrum was studied,the influence of the periodic evolution characteristics of the vibration spectrum of the sanding device on the service life of the sanding device was discussed.The main conclusions are as follows:(1)Combined with the vehicle system dynamics and the rigid-flexible coupling dynamic model of the sanding device,the random vibration model of the sanding device is established by using the pseudo-excitation method based on the PID control method to reproduce the actual vibration environment.Using this method,the dynamic stress of sanding device obtained by both simulation and vibration test were compared.The results showed that the simulation and test results are in good agreement,which suggested that the random vibration model of the sanding device established in this thesis can reflect the actual vibration level of the sanding device.(2)The vibration characteristics of the axle box were analyzed on the Chengdu-Guiyang railway and compared with the loads defined by the standards(EN 13749 and IEC 61373).The results showed that the standard loads cannot describe the service load environment of the axle box on the Chengdu-Guiyang railway.The IEC 61373 standard vibration spectrum ignores the vibration energy of 500～1000 Hz,overestimates the vibration level of 20～300 Hz,and underestimates the vibration in the range of 300～500 Hz.Considering the distribution of wheelrail characteristic frequency bands,the characteristic frequency bands of axle box were defined as 20-150 Hz,150-300 Hz,300-500 Hz,500-700 Hz,and 700-1000 Hz.The defined vibration spectrum can serve as the basic input random vibration fatigue assessment.(3)Based on different frequency domain life evaluation methods,the structural damage of the sanding device was analyzed considering standard and measured vibration spectrum.The results showed that the Dirlik method and the Zhao-baker method can better estimate the distribution of the stress amplitude the sanding device.The damage of the sanding device calculated based on the IEC 61373 standard vibration spectrum was much lower than that caused by the measured vibration spectrum,because the standard vibration spectrum underestimates the vibration energy in the frequency range of 300～700 Hz.The evolution characteristics of the vibration spectrum of the sanding device with mileage were studied,and the periodicity caused by wheel reprofiling was considered,and a stochastic evolution model that could describe the periodic evolution of the vibration spectrum of the sanding device was established.The Monte Carlo method was used to study the damage of the sanding device considering the periodic evolution of the load,was predicted the damage and reliability evolution process of the sanding device during the service period.