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Spot welding is a process in which contacting metal surfaces are joined by the heat obtained from the resistance to electric current. Work-pieces are held together under the pressure exerted by electrodes. The process uses two shaped copper alloy electrodes to concentrate the welding current into a small spot and simultaneously clamp the sheets together. Forcing a large current through the spot melts the metal and forms the weld.

Our study provides a finite element model to predict the nugget development during resistance spot welding of steel sheets. The model employs the coupled thermal-electrical-mechanical analysis capability of Abaqus. The contact area and the interface pressure distribution are determined from a thermal-mechanical coupling in the analysis. The knowledge of interface pressure allows for accurate prediction of interfacial heat and electrical resistance, which have a dominant role in Joule heat generation. Temperature-dependent material properties for the coupled analysis are used.

The significant parameters in the spot-welding process are current magnitude and frequency, welding time, sheet material and thickness, geometry of electrodes, and electrode force. The methodology developed in this paper demonstrates the applicability of Abaqus to predict the shape and size of weld nuggets with variation of each process parameter using standard input options. Using this methodology assists in adjusting welding parameters so that costly experimental works can be avoided.

Note for the animation file; Gray area represents the generated nugget. Oscillation can be seen because the current input is sinusoidal.

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