Study On The Crack Propagation Life Of Bogie Frame Under Multi-axis Stress State

The subway is the most convenient and economical urban transportation facility and mode of travel.Considering its importance in the daily traffic of the city,the reliability and safety of the key structures of subway vehicles have extremely high requirements.The bogie frame is one of the most important structures in the parts of subway vehicles,and it is the main load-bearing component of rail vehicles.In order to meet the reliability and safety of the vehicle,it is necessary to study the fatigue life of the bogie purchased frame.The main research contents of this paper are as follows:(1)The bogie frame is selected as the research target of this paper.According to the standard U615-4,the maximum stress position of the frame under static strength loading and fatigue strength loading is calculated according to the standard U615-4,and the theoretically dangerous parts of the frame are determined;(2)Carry out dynamic stress test on the bogie frame,collect the dynamic stress data of the key parts of the frame during the operation of the frame,use the software to process the data,and use the Miner linear cumulative damage criterion to calculate all the measured points Equivalent stress amplitude,compare the equivalent stress magnitude of each measuring point,and determine the dangerous parts of the structure during actual operation;(3)According to the foregoing,determine the critical hazard part of the frame to select the initial crack location where the crack propagation life needs to be studied,and in combination with the standard BS7910,carry out the safety assessment of the structure where the crack propagation is studied.According to the 2A level in the standard,the safety assessment curve and safety assessment diagram here are calculated,and the crack modes of different lengths and depths are simulated for safety assessment,and the conditions under which the crack fails here are obtained,which provides a basis for the following crack propagation;(4)Combining the dangerous parts of the frame mentioned above,use finite element simulation to determine the multi-axial stress of the frame and determine the loading conditions of the frame.Determine the parameters and conditions required for crack growth,combine the results of the structure failure caused by the crack growth in the previous section,use limited software to simulate the crack growth of the dangerous part according to the stress spectrum obtained in the previous section,and calculate the cycle times of the crack causing the failure of this position.In this way,the operating life when the framework fails is obtained.38 figures,23 tables and 70 references.