Analysis Of Random Vibration Fatigue Strength Of Bogie Frame

The characteristics of modern railway vehicles are the high speed of passenger transportation and the heavy load of freight.As the speed and load increase,the actual operating conditions of railway vehicles become worse,and the vibration of the vehicle system is more intense,the vibration is random,vehicles which are in a random vibration environment for a long time are prone to fatigue damage and affect the normal use of the vehicle.The bogie frame is an important part of the vehicle,which directly carries the car body and is stimulated by the wheel pair.Therefore,the fatigue resistance of the frame is significance to the safe operation of the rail vehicles.In this paper,the dynamic vibration and finite element co-simulation method is used to analyze the random vibration fatigue strength of the CRH3 EMU bogie frame and predict the life.First introduces the concept of random vibration,and enumerates the method of analyzing random vibration fatigue problem in frequency domain.Finally,the three-interval method in frequency domain is used to analyze the random vibration fatigue strength of the bogie frame.Next the method of establishing multi-body dynamic equation of motion is introduced.The single-vehicle model of CRH3 EMU is established by SIMPACK,and the nonlinear critical speed of the model is calculated to determine the stability of the dynamic model.Load the actual measured orbital irregularity power spectrum and perform the integral calculation,finally the vibration acceleration excitation of the bogie frame is obtained.Secondly,the basic structure of CRH3 EMU bogie and frame is introduced.The finite element theory is used to discretize the frame.The spring unit is used to elastically constrain the frame.The static strength calculation is carried out in ANSYS.Finally,under the effect of static strength load,the structure has not broken.Finally,the finite element modal theory is introduced and the constrained modal analysis of the frame is carried out in ANSYS.The acceleration power spectrum is obtained by the SIMPACK fast FFT function,and the vibration response of the frame under random acceleration excitation is obtained by the modal superposition method.According to Steinberg's three-interval method,cumulative damage theory and IIW standard,Calculate the damage value of the maximum stress at each welded joint of the frame and the fatigue life of the frame is predicted.In addition,This paper also analyzes the effects of longitudinal excitations,lateral excitations and vertical excitations on the damage of the frame.