Research On Crack Growth Life Of Key Parts Of EMU Bogie Frame

With the gradual increase in the number of EMUs,the number of EMUs that have required advanced repairs for many years in service has also increased.Because of their high operating mileage,the operational safety and maintenance strategies after advanced repairs have become issues of concern.Bogies with harsh service environments have become the key components for research.This paper takes the CRH380 A EMU bogie frame as the research object,and based on the measured dynamic stress data of this type of EMU line,it conducts a study on the crack propagation life of key parts of the EMU bogie frame.The operation safety guarantee and its reasonable maintenance methods have certain reference significance.The main research contents of this article are:(1)For the CRH380 A EMU bogie frame,use UIC615 and EN13749 standards for finite element analysis,the purpose is to determine the location of the frame's large stress;(2)Carry out line tracking test on the 13-car 2-position EMU bogie of CRH380AL-2586 EMU of Wuhan Bureau,collect dynamic stress data of 75 measuring points,and complete the corresponding data processing work;(3)Adopt the method of virtual calibration to obtain the transfer coefficient of the corresponding measuring point and the main load of the test frame;(4)Briefly introduce the ill-conditioned matrix problem encountered in the process of load identification,and the method of adopting the regularization method to solve the problem.The L-curve method and the GCV method are used to calculate the regularization parameters,and then the Tikhonov regularization method is used for inversion.And the truncated singular value method was used to invert the main load,which confirmed the feasibility of the regularization method in identifying the bogie load;(5)Simulation analysis of the bogie frame with crack defects using the identification load,focusing on the two corners of the arc corner of the upper cover plate of the longitudinal auxiliary beam and the position of the welding seam between the positioning seat and the lower cover plate of the side beam.Simulation and actual measurement confirmed that the cracks were implanted at the location under high stress,and the extended life was estimated using a quasi-static method.The results show that crack growth life of the weld end at the connection between the positioning seat and the side sill lower cover plate is low,and it is in operation.Special attention should be paid to the process and maintenance.