Abstract: The spot welding of aluminum alloy is a high nonlinear multi-physical process. The contact resistance have both the random distribution and high nonlinear variation characteristic. With the study of the electric contact characteristic, a new numerical model of the contact resistance is presented. Based on this new model，the initial temperature field of the alumin-um alloy spot welding is simulated by FEM. The result indicates that within the first quarter cycle the temperature field is inhomogeneous severely and the electrode wears out and the splashing mainly in this period. From the FEM result, it also can be obtained that the nugget is formed during the first half cycle mainly and it is hard to obviate the wear of the tip in spot welding of aluminum alloy.

Key words: Temperature field, Aluminum alloy, Spot welding