Numerical Simulation Research On Welding Of Transformer Box Structure In Locomotive Under Different Constraints

Today, science and technology develop rapidly, and welding technology has become an important topic. With the constantly development of welding technology, welding components are more and more diversified and complicated, and box structure is one common kind of these welding components. Box welded structure has appeared in the daily life in various fields, especially in construction machinery fields. The residual stress and deformation are produced because of nonuniform heating of the box structure. However,the welding residual stress will influence the rigidity and stability of the product, leading to reduce the load capacity of welded components. Welding deformation will change the structure of the weldment size and shape, which can affect the quality of the product.Therefore, the study of welding residual stress and deformation become a major issue in the welding field, which has important guiding significance to practical engineering.Lots of Domestic and foreign scholars studied the problems of welding residual stress and deformation, and made a lot of research results. But these methods can be divided into three types:empirical method,analytical method and numerical simulation method.With the development of numerical calculation technology and the development of finite element software,finite element method has occupied a dominantposition in the welding research.This paper briefly describes the present situation and problems of development of welding numerical simulation research at home andabroad,and discusses the welding finite element analysis theory in detail. The numerical simulation of welding residual stress and deformation on box structure was realized successfully by use of the finite element analysis software ANSYS.The main research contents of this paper are as follows:1) The fields of the welding temperature and the stress for the plate butt welding were analyzed and compared by the numerical molding under four different constraints. After that, the optimum values which suited to the plate butt welding were obtained. Meanwhile, by analysis of the wave deformation in a free state, it was found that the maximum deformation with a value of2mm for the plate butt welding was appeared in the Y direction.2) The welding temperature field and stress field of tee joint are simulated under four different constraints and the results are compared. Meanwhile, the angular distortion is analysed. The deformation on the web is obvious, and the first kind of scheme of deformation is the largest. In the vertical direction of the weld, the maximum deformation of AC side is0.35mm.3) The temperature field and stress field of box structure are simulated under three plans and the results are compared. At the same time, the residual stress and distortion of welding are analysed. After welding, the deformation of box structure is similar to arch, and the maximum deformation appeared in the middle of the plate. The maximum deformation of first solution is2.14mm, the second is1.986mm, and the third is1.862mm.4) The welding temperature field and stress field of the box structure are simulated under two plans and the results are compared. At the same time, the residual stress and deformation after cooling are analysed. The deformation of second solution is significantly greater than the first solution, and the maximum deformation of the second solution is2.19mm.