A THEORETICAL-STUDY ON ELECTRICAL AND THERMAL RESPONSE IN RESISTANCE SPOT-WELDING

The effect of contact resistance including constriction and contaminat ion resistance has been a major hurdle for the thermoelectrical analys is of the resistance spot welding process. In this paper, a simple mod el was suggested and used for calculating the electrical and thermal r esponse of the resistance spot welding process to investigate the infl uence of contacting forces on the formation of weld nuggets. The elect rode surface of the contact interface was assumed to be axisymmetric a nd its micro-asperities to have a trapezoidal cross-section. These mic roasperities were considered as the one-dimensional contact resistance elements in the finite element formulation. The contamination film wa s assumed to be a nonconducting oxide layer, which is very brittle, so that it is broken to some number of pieces when a contacting pressure is being applied. The crushed films were assumed to be distributed at regular intervals and to conserve their size and number during the we lding process. The simulation results revealed that the proposed model can be successfully used to predict the effect of the contact resista nce on the electrical and thermal response of the resistance spot weld ing process.