Fatigue Strength Evaluation And Random Vibration Analysis Of EMU Axlebox

With the development of our country’s economy and the increase of market demand,the operation speed of EMUs has been further improved.As an important component of the bogie,the axle box faces problems such as harsh working environment,complex and changeable loads,and occasional fatigue failure when the EMU runs at high speed.In order to ensure the driving safety,it is of great significance to study the fatigue strength evaluation and life evaluation of the axle box.In this paper,a certain type of EMU axle box in my country is taken as the research object,and its fatigue strength evaluation and random vibration analysis are carried out to ensure its safety in service.The main research contents of this paper are as follows:(1)Using UM software for dynamic modeling,the orbital irregularity power spectral density function expressed by piecewise function is obtained according to the TB/T3352-2014 standard.According to the line data of the pilot section of the Beijing-Shanghai high-speed railway,a line combination model is simulated.After the UM modeling,the static balance,stability,and curve passing tests of the model were carried out,and all data tests were obtained,and the model met the requirements.According to the actual operating conditions,the maximum operating speed of 310km/h is selected to simulate the output axle box load and acceleration.The acceleration power spectral density PSD is obtained by using the data post-processing function of UM.(2)In order to ensure the service safety of the axle box,a comparative analysis was carried out against different standards such as EN 13749,UIC615-4,JIS E 4207 and EN12082,and their use ranges,load types and working condition combinations were obtained.Through the solid modeling of the axle box and the finite element simulation analysis,the stress size and distribution of the axle box under 20 different working conditions were obtained,and 12 fatigue weak points were obtained.The modified Goodman curve was used to evaluate the fatigue strength of the axle box.The results show that the fatigue calculation stress of all nodes on the key stress region of the axle box does not exceed the Goodman-Smith fatigue limit range,which meets the fatigue strength design requirements.(3)The life prediction is based on the S-N curve of the material and the linear cumulative damage theory,with the help of the n Code analysis software,the fatigue characteristics of the ductile iron material and the UM simulation output load are used to predict the life of the axle box.The results show that the fatigue life of the area where the stress concentration of the axle box is relatively small,the connection between the arm and the rubber joint positioning ring and the connection between the primary steel spring support seat and the bearing hole where the minimum life of the axle box occurs does not exceed the EN 13749 standard.Most areas of the axle box are in a safe state.(4)ANSYS Workbench was used for modal analysis,and based on IEC 61373-2010 standard power density spectrum and UM output power density spectrum,impact load and random vibration load fatigue analysis was performed.The results show that the maximum stress occurs at 0.018 s and does not exceed the yield strength of the material under the impact load condition.Under the random vibration load condition,the fatigue life failure criterion D of the axlebox is evaluated according to the Miner linear cumulative damage theory and the ductile iron S-N curve,and it is found that it is all less than 1,which meets the fatigue requirements.