Research On Fatigue Reliability Of EMU Gearbox Body

As an important component of the key parts and transmission system to ensure the continuous and stable operation of the EMU,the structural fatigue performance of the gearbox directly affects the operation safety of the EMU.The fatigue failure is the main failure mode of the gearbox in the service process.In view of this problem,this paper takes the gearbox housing of the EMU as the research object.Through the strength analysis,life prediction,reliability evaluation and topology optimization of the gearbox housing,it provides reference for the structural design and anti-fatigue design of the gearbox housing of the EMU.The specific research contents are as follows :(1)According to the performance characteristics and structural parameters of the gearbox,the finite element model is established.According to the EN13749 standard,the load calculation of the positive and reverse working conditions under the starting and short-circuit conditions is determined,and the strength analysis of the box is carried out by using the finite element analysis method.The analysis shows that the maximum stress value of the box under four different working conditions does not exceed the yield strength of the material.Based on the maximum principal stress method,according to the TJ / JW 064-2015 standard,the Goodman curve is used to check the fatigue strength of the box.(2)In order to obtain the dynamic response characteristics of the gearbox,the modal analysis of the gearbox is carried out to obtain the natural frequency and vibration mode of the gearbox.Considering the influence of external load excitation on gearbox vibration,the first ten modes and corresponding frequencies are obtained.The first-order natural frequency is 505.0 Hz,and the overall lateral deformation mainly occurs.Combined with the results of modal analysis,the harmonic response analysis of the box is carried out under the two lines of high-speed straight line and turnout.The analysis results show that the vibration peak will be generated near 535 Hz,which will affect the normal operation of the gearbox and provide a theoretical basis for the study of the dynamic characteristics of the gearbox.(3)Based on the S-N curve and the measured load spectrum,the n Code＿Design Life analysis software is used to analyze the fatigue life of the gearbox,and the fatigue weak area of the gearbox is obtained,and the overall life prediction is completed.Based on the firstorder quadratic matrix theory,the material,size and load are selected as random variables to analyze the reliability of the box under different working conditions.The results show that the reliability of the gearbox is 0.99,which meets the requirements of safe operation under different working conditions.(4)In order to realize the lightweight design of the gearbox,the finite element analysis software is used to combine the static strength results and the extracted modal analysis results.The minimum volume is taken as the optimization goal.According to the material arrangement scheme under different material volume distribution,the gearbox body reinforcement structure is designed,and the strength and modal analysis of the optimized box are carried out.The results show that the stress value of the optimized model is reduced under the conditions of starting forward and reverse rotation and short circuit forward and reverse rotation,and the strength and stiffness of the optimized gearbox housing are improved,and the quality of the housing is reduced by 0.76 %,which provides a certain reference for the design of the gearbox.