Numerical Study of Shunting Effect in Three-steel Sheets Resistance Spot Welding

The main purpose of the present research is to investigate the shunting phenomenon in a three-sheet RSW joint using finite element simulation. To this end, a three-sheet resistance spot welding joint was simulated as an electrical-thermal-mechanical coupling problem. To validate the presented simulation, the finite element results were compared with the experimental results, including nugget size and geometric shape in the resistance spot welding joint. Afterwards, the multi-spot welds of three-sheet low carbon steels with the same thicknesses were analyzed considering the sequential distance of 45 mm. Various techniques, including new spot-weld diameter measurement, electrical current density, electrical contact conductivity, and electrode displacement, were used to study shunting effects in the process of consecutive spot welds. The results obtained from different methods have greatly matched each other. Also, finite element results indicated that the assumption of neglecting the sheet deformation effect for low intervals between consecutive spot welds is acceptable. However, it is necessary to consider sheet deformation for distance intervals more than 45 mm.