The Numerical Simulation Of Welding Deformation Of Spot Welding Joint

In this paper, the welding deformation of resistance spot welding of stainless steel was studied, using ordered coupling style to realize the multi-physical fields coupled simulation analysis, and finally realizing predict welding deformation results of resistance spot welding of stainless steel by inherent strain method.In this dissertation, a two-dimensional symmetric model was built for contact preloading analysis of resistance spot welding of stainless steel. Through contact preloading analysis: the contact pressure peak near the edge of the electrode end on the contact surface, which is gradually increased with the increasing stress of electrode contact pressure, and the location of stress peak are basically the same; the radial coordinates of abutted surface contact pressure peak point is smaller than the electrode end of the radial coordinates, with the electrode stress increasing, the contact pressure of abutted surface increases too, and the location of abutted surface contact pressure peak point appears near to the axis of symmetry. Obtained initial conducting area via numerical simulation of resistance spot welding of stainless steel,. which lay the foundation for electrical-thermal coupled analysis.Building the electrical-thermal coupled analysis model based on contact preloading analysis, simplifying the contact resistance of the contact surface and abutted surface as a function of temperature, considering the parameters of physical-thermal properties, which depend on temperature, to analyze the transient temperature field of stainless steel sheet resistance spot welding process. Through the electrical-thermal coupled analysis: nugget formation process, temperature field distribution, the electric potential distribution as well as the nugget migration caused by welding different thickness plate, which is the same as the actual welding result. Temperature field analyzing result can be used as initial load of the thermo-mechanical coupled analysis. Building the thermo-mechanical coupled analysis model based on electrical-thermal coupled analysis, Through the thermo-mechanical coupled analysis: In the spot welding process with the same thickness, because of model symmetry, strain and deformation are symmetrical distribution; but in the spot welding process with different thickness, because of the model asymmetry, strain and deformation are asymmetric distribution, and analysis of various parameters on the welding deformation, which lay the foundation for analysis of spot welding deformation via the inherent strain method.Introduction of inherent strain method analysis of welding deformation based on the thermo-mechanical coupled analysis results. First, the inherent strain method is applied to analysis of seam welding process, to prove the reliability of the inherent strain method. And then introduction of the inherent strain method to spot welding deformation analysis, from two-dimensional to three-dimensional, from a single point-to-multipoint, and gradually in depth. Designed a typical spot welding joints using the principles of equal strength, and analyze welding deformation by inherent strain method: the deformation of structure with multi-spot rather than the deformation of single spot simply linear stack; at multi-spot welding joints, the smaller the dot pitch, the larger welding deformation gradually become, the greater the distance, the smaller welding deformation appeared; the greater the col width, the smaller welding deformation appeared, the smaller the distance, the larger welding deformation gradually become. Finally, it proves the inherent strain method can be used for welding deformation analysis of large-scale structure of the spot welding.