Research On The Crack Propagation Life Of Key Parts Of EMU Car Body

With the substantial increase in the running volume and running mileage of high-speed EMUs,the maintenance and safety assessment of EMUs have been put on the agenda.Up to now,a large number of EMUs have entered the fifth-level repair process.It is of great significance to study the service status and safety laws of the EMU structure.This article selects the car body structure of CRH380 A EMU,With the help of finite element analysis software to complete the strength analysis and fatigue crack growth analysis,combined with the SINTAP / FITNET safety assessment method based on the FAD failure assessment chart,the safety status and remaining life of critical parts of the car body were evaluated.The CRH380 A EMU car body is selected as the research object,and the car body finite element analysis model is established.The boundary conditions are determined according to the "Temporary Provisions for Strength Design and Test Appraisal of Railway Vehicles at 200km/h and Above",pre-process and load in Hypermesh software and analyze and calculate in ANSYS software to complete the static strength and fatigue strength analysis.The calculation results show that the static strength and fatigue strength of the car body structure meet the requirements,and the connection between the chassis traction beam and the crossbeam is a key part of the car body structure.The load-stress transfer coefficient of the key parts is obtained by finite element simulation calculation,and the ill-conditioned problem of the transfer matrix is avoided by the truncated singular value decomposition method;the dynamic stress tracking test of the line is carried out on the key parts of the chassis,and the dynamic stress is obtained The data is used for load identification,and the actual values of the vertical load,longitudinal compression load of the coupler,longitudinal tensile load of the coupler,local load of the center pin and torsional load are obtained.Using the extended finite element method in Abaqus,a finite element model of the car body underframe beam is established,and the actual vertical dynamic load identified is used as an input for crack propagation calculation,and the remaining life of the beam structure under different initial crack lengths And the corresponding crack growth size.Through the SINTAP safety assessment method based on the FAD failure assessment chart,the safety assessment of the welded parts of the traction beam and the crossbeam of the car body chassis was carried out.The evaluation results show that,assuming that the crack form is a semi-elliptical surface-type crack,the value of the crack shape has little effect on the safety of the structure,and the main parameter that affects the safety evaluation result is the crack depth;and based on this The critical crack size of the welding part of the traction beam and the cross beam is 5.3?5.7mm.This evaluation method provides an analytical idea for the evaluation of the remaining life of the service structure.Figure 43,table 28,reference 54.