Thermal Shaping Simulation Of Welding Structure In Railway Vehical

Light weight welding bogie frame is the key carrying components of a modern locomotive vehicle, Its strength on the reliability play a decisive role on the service security locomotive vehicle. The main bearing components of lightweight welding bogie frame is box plates welded structure. In the welding process, due to the heat increasing instantaneous dramatically, then cooling at environment temperature, there was a significant residual stress occurring on the molding structure. In order to reduce welding residual stress and welding deformation, and optimize the welding process, the study of molding process of welding has a high processing value and engineering significance.As heat transmit very quickly in metal materials,highly concentrated heat can only melt a welding parts, so the welding temperature is very uneven and unstable, and this is the cause of the residual stress and deformation. As a result of the uneven distribution welding heat in time and space, so more precise simulation of welding process needs very fine mesh and very short time step on the region of welding area. In addition, due to a high nonlinearity of geometric and material causing the difficult convergence, it have to increase the number of iterations and the lengthy computation time.This paper describes the international situation on the welding temperature field and the associated stress field, and the difficulties in numerical simulation of welding and application of new technology, the basic FEA theory of welding temperature, welding residual stress and deformation. In order to simulate the welding process more accurately, this paper study the proper heat source model of fillet weld, it use several heat source models to simulate welding process of fillet weld, by comparing the results, The most suitable heat source model is the uniform heat source model. For large welded structure, the finite element model is very large, and need refined mesh near the weld area, the calculation need lengthy time and large disk space. For this problem, it use sub-structure technology to simulate welding process, in the weld and near the region of it, the results of whole structure and sub-structure show basically the same residual stress, and slightly different in areas far from the weld, but this effect on the results scarcely. More closed result to full-structure calculation can be achieved while choosing RESOLVE sub-structuring expansion method.Finally, through the numerical simulation of 6 main weld in the side beam of one subway power bogie frame, it get the variety discipline of the welding temperature field and the dynamic stress and deformation, and residual stress and deformation after cooling. It make the accurate numerical simulation of large welded structures in 3D finite element model to be reality, laid the foundation of numerical simulation of large welded structures for welding workers, has great theoretical and practical significance in engineering application.