Process and structural models for resistance spot welding

Abstract

Resistance spot welding is an important joining process in many industries such as the automotive one. Advantages such as speed and flexibility in fabrication are counteracted by limits on its structural integrity, which arise from the inevitable formation of residual stresses [1]. The inherent melting and re-solidification of the material cause large thermo-mechanical loads that, at the end of the cycle, leave residual stresses present in the welded components. If no post welding heat treatment is performed, these residual stresses interact with the structural loads imposed on the component. Finite element analysis models can be used to predict the formation of residual stresses and the stress field present in the loaded component. In this paper different modelling strategies are presented and assessed on a simple case study consisting of two flat mild steel sheets joined by a single spot weld.