Esmaeil mirmehdi - Professor of Mechanical Engineering, technical and vocational university golpayegan,

Spot welding is one of the types of resistive welding and it is used for welding of sheets. The thickness of sheets welded by the spot welding method can be between 0.5 and 3 mm. In spot welding two copper electrodes are similar, It is used to focus the current on the sheet and to apply pressure on the sheet. Spot welding is used in a variety of industries including automotive, aerospace, etc. In this paper, the finite element method for non-destructive spot welding test is simulated. It has been investigated ultrasonic propagation in two layers of stainless steel, galvanized stainless steel sheets and two sheet layers non-similar of stainless steel and galvanized stainless steel sheet in different thicknesses. This test was performed by ultrasonic immersion method and the intensity and amplitude of the reaction of the resulting defect waves and its effect on the results were also investigated. Comsol Multiphysics software is used to solve the finite element in this article. It has been studied various factors and conditions including excitation frequency, boundary conditions, the most suitable position for the probr to stimulate the waves, focused or unfocused waves in the simulation, sensitivity analysis of mesh size and appropriate mesh size for simulation. Similar and non-similar sheets are used in different industries. In this paper, the joint of similar and non-similar sheets is investigated. For this performance, the average relative error that can meet the industrial requirement is mentioned. The results of the simulation are compared with the experimental results and good agreement between them is observed.

Spot Welding, Ultrasonic Waves, Finite Element, Simulation, Similar Sheets, Non-similar Sheets, Focused Waves, Unfocused Waves