Study On Stress Characteristics And Fatigue Life Of Subway Bogie Frame Under Random Vibration

With the increase of traffic volume and operation speed of metro vehicles,the dynamic force between wheel and rail increases,and the vibration of vehicle structure intensifies,which brings potential harm to the safety of vehicle operation.Therefore,it is very important to study the influence of vibration on the stress response and fatigue life of vehicle structure.In this paper,taking Beijing metro vehicle bogie as the research object,combined with the line test and modal analysis,the measured dynamic stress characteristics of the bogie are obtained,and the main frequency source of stress is analyzed;the stress response characteristics of the bogie under the three-way acceleration of the axle box and the three-way acceleration of the electric machine are calculated by the random vibration simulation analysis method,and the main frequency of stress is obtained;combined with the time-domain damage compilation The main work is as follows: 1(1)The frequency spectrum analysis and frame modal vibration characteristic analysis of the measured dynamic stress signal of the line at the connection of the transverse side beam,the connection of the motor suspension base and the cross beam,and the connection of the gearbox suspension base and the cross beam are carried out.Combined with the measured axle box acceleration signal and the motor acceleration signal,the main frequency source of the frame dynamic stress is obtained.The results show that the stress amplitudes at 48 Hz,57Hz and 75 Hz are large.During the operation of the line,the excitation frequency of the axle box acceleration is 57 Hz and 75Hz;when the operation speed reaches 60 km / h,the excitation frequency of the motor speed is 48 Hz,and the excitation frequency coincides with the natural frequency of the frame,which results in the excitation of the modes at 57 Hz and 76 hz in the actual line conditions,and the measurement points generate large stress amplitude at the corresponding frequency.(2)The random vibration simulation analysis of the frame under the axle box acceleration and motor acceleration is carried out,and the stress power spectral density is obtained.The results show that the greater stress response is obtained near 57 Hz and76hz at the measuring points of each area,which further proves that the mode of the frame at 57 Hz and 76 hz is excited.(3)In the time domain damage editing method,the damage retention percentage is99% and 99.9% respectively,and the damage values in time domain and frequency domain are compared and analyzed.By using the time domain and Dirlik frequency domain calculation methods,the measured dynamic stress damage calculation is carried out at the joint of transverse beam,the joint of motor suspension seat and beam,the joint of gearbox suspension seat and beam,and the joint of primary spring installation seat The time-domain and frequency-domain damage errors of the test points are all within the acceptance range,which verifies the feasibility of the frequency-domain damage assessment method and obtains the fatigue life of the frame.44 pictures,10 tables,62 references...