Fatigue life prediction of multi-spot-welded panel structures using an equivalent stress intensity factor

Abstract

Fatigue failure of spot-welded panel structures can be evaluated by means of a fracture parameter, since a weld-spot has an external crack type geometry. Recasting the load vs. fatigue life relations experimentally obtained from single-spot-welded specimens, we predict the fatigue life of spot-welded specimens with a parameter denoted the equivalent stress intensity factor ( K e). This crack driving parameter describes the effect of material ductility, specimen geometry and loading type on the fatigue failure in an inclusive manner. The proposed fatigue life formula for a single spot weld is used for assessment of multi-spot panels, as the fatigue strength of multi-spots is eventually determined by that of each constituent single spot. In this study, we consider three types of multi-spot seat belt anchors as analysis models. We obtain the effective crack driving parameter K e using finite element analyses. The K e concept is then confirmed to successfully predict the fatigue life of multi-spot panels represented by auto seat belt anchors here.