Local Fatigue Life Research On Tne Motor Mount Of EMU

Nowadays,the operating speed of passenger trains in our country continues to increase,then the relevant standard for verifying the fatigue strength of the bogie frame have not been significantly changed in recent years,and there is no clear solution to the local fatigue load.This article used a bogie frame of high-speed train as an example,and the research was started from the local fatigue strength of motor mount,based on the simulation analysis,line test and bench test.According to conditions of relevant criteria,just as UIC 615-4,for the local fatigue standards made out,and the frequency range of applicable load analysis in the standards,the acceleration signal of motor was filtered and divided into two categories: low frequency load and high frequency load.The former was used to compare the difference between the structural damage obtained by the standard fatigue loads,and the high-frequency load was used to obtain the difference of the structural damage whether contained the consideration of resonance conditions.In the low-frequency load fatigue analysis,the data were obtained at different stages of the train's entire operating cycle after the wheel's repair,to ensure that the data sample is sufficiently adequate.Structure damage was worked out through the rain flow counting method and quasi-static stress response.According to the local fatigue load scheme in common standards currently,the corresponding load spectrum was compiled to obtain the structural fatigue damage under different schemes;the comparison of the structure damage in two cases whether the main body fatigue and local structural fatigue were synchronous or stepwise;it could be seen that the structural damage under the low-frequency load spectrum was lower than the structural damage under the standard load spectrum,and the result of stepwise loading mode was larger than that obtained through the synchronous loading mode,so the stepwise loading mode was more conservative.In the high-frequency load fatigue analysis,with the result of the structure harmonic response,and the structure damage was obtained by excitation in different directions through the frequency domain method.Due to the transverse instability in the train operation,more violent transverse vibration of the motor would be caused.So a set of acceleration signals when the frame was in lateral instability was selected,and the influence on the structural damage was evaluated under the lateral instability state.Therefore,the lateral instability should be considered in the strength assessment.This paper synthesized the standard fatigue test method of the frame motor mount,the random load method inference by the line-measured acceleration data of the motor and the influence of failure conditions like lateral instability,then the recommended fatigue load value was given,and the fatigue life of the motor mount was assessed.This article has a certain reference value for future research.