A Theoretical Model for the Elastic-Plastic Behaviour of Spot Welded Joints

An analytical procedure for the evaluation of the elasticplastic behavior of spot welded joints is presented. The procedure is based on a new theoretical model of spot weld region: a circular plate having variable thickness with a central rigid nugget. The closed-form solution allows to describe the displacement of a rigid nugget when an axial orthogonal load is applied on the plate while plasticity and moderately large deflections are present. The goal is to reach a reliable spot weld region model which can be used as the basis to develop a spot weld element in FE analysis even when plasticity and large deflections are in effect. The analytical results obtained by using the new general relations precisely match those obtained modelling spot weld area by FEA.