A Novel Fatigue Analysis Method of Welded Frames

In order to evaluate the fatigue strength of welded bogie frames under multi-axial stress in load cases, a tensor method based on the direct method and projection method was proposed by applying coordinate transformation property of the second-order tensor. This method, by transforming multi-axial stress to the same coordinate system and the same section, uses the obtained maximum stress and minimum stress for the fatigue evaluation. The finite element model was then built based on a certain welded bogie frame. The stresses in several static conditions were calculated. For comparison purpose, the direct method, projection method, and tensor method were used to evaluate the fatigue strength of this bogie frame, respectively. The rationality of the three methods was verified by critical plane approach and Ncode. The results show that the tensor method, which took the direction of multi-axial stress into consideration, is obviously better than the other two methods, with the smallest error of 4.42% compared with the Ncode result.