Numercial Simulation Of The Precess Of Aluminum Alloy Resistance Spot Welding

Aluminum alloy preferred in the fields of automobile manufacture and aviation with its little density and large specific strength. But,the application of aluminum alloy resistance spot welding (RSW) in these fields is impeded by weld quality and electrode longevity. The process mechanism research of aluminum alloy RSW is the basis of solving these problems.The instantaneity of RSW process make it difficult to experiment research of the nugget growth process and it is unbelievable to only numerical simulation. So,the numerical simulation with a little experimental verification is implemented to investigate the process mechanism of aluminum alloy RSW in this thesis. The mechanical,thermal,electrical behaviors during the process of aluminum alloy RSW are analyzed,which provides the theoretical basis for solving welding problems.According to elastoplastic and contact theory,an axial symmetry finite element model of pre-squeeze contact analysis for aluminum alloy RSW with cone-shaped electrode is developed. The contact behaviors in pre-squeeze stage of aluminum alloy RSW are simulated and the initialized conducting region is decided by this model. Base of this,according to the basic equation of depicting RSW process, an axial symmetric finite element model of mechanical,thermal and electrical coupled analysis for the process of aluminum alloy RSW is developed in this thesis based on the finite element theory. The mechanical,thermal and electrical coupled analysis is accomplished by using the APDL tool. In this model,the thermal physical properties,the latent heat of phase change are considered and the variation rules of contact faces, current density and temperature field during the process of aluminum alloy RSW are discovered quantitatively.On the base of above results for these numerical simulation. Aluminum RSW experiments are executed in same welding condition with numerical simulation and the experimental nuggets are checked and measured. The results testified: computational nugget diameter,shape and penetration agree well with those from experiments,which show that the models and simulation results in this paper are exact.