Fatigue Analysis Of The Residual Stress In Welding Frame

Residual stress of welding and distortion, two important factors influencing the structural performance and safety reliability of bogies, do disadvantageous effects on precision of the shape and the size. As the main component of locomotive, the bogie plays a vital role for traffic safety. And the bogie frame, welded by box beam, is the main carrying and transferring power part of a bogie. Then, how to precisely test or simulate the residual stress of welding bogie frame, and analyse its influence on fatigue strength has a high engineering value on improving the carrying capacity of the bogie frame, expanding its service life the bogie frame and enhance its operation safety.The thesis reviews the characteristics of numerical simulation about welding residual stress as well as the status quo and the development of welding stress research both at home and abroad. And mathematical models and finite element methods for welding temperature field and stress field are given in this thesis on the basis of the finite element analysis software ANSYS.Aiming at solving problems that there are lots of calculations for the welding residual stress simulation of the main structure of welding bogie frame, and it is difficult to determine the time step, and the results are difficult to converge, the author researched element, mesh, time step and boundary conditions, and use regular shaped 3D solid hexahedron element without middle node to mesh, and refine in the near heat region and sparse in the far heat region, which enhances the evaluating efficiency. It is difficult to simulate heat source and the filling process of the metal, the present thesis gets the results matching with the classical theories by using the birth-death element method to simulate the metal filling process. The thesis-also gets results of the welding temperature field, heat stress field and residual stress of the T-shape welded joints and box beam structure by Gauss Heat source model, and by APDL program to simulate the heat source movement, which provides evidence for the feasibility study of the numerical simulation of complex welding structure.By making a comparison of different techniques and instruments of testing the residual stress, the present thesis proposes instruments and schemes for testing residual stress of welded structures; based on a comparative study on elimination techniques of residual stress of welded structures, the thesis puts forward elimination techniques suitable for welded structures.