Assessment of welded structures by a local multiaxial fatigue approach

Abstract

A new local multiaxial computing method for the fatigue assessment of welded structures is presented. This approach is based on the use of an equivalent stress derived from the multiaxial fatigue criterion proposed by Dang Van for plain machined specimens. Application to fillet welds allows a better description of the influence of local geometries and residual stress states. These factors are related to the weld process and the quality of the weld. This approach, associated with definite shell finite element meshing rules in order to take account of the increase of local rigidity introduced by the weld, is also successfully used to assess the fatigue resistance of welded automotive structures.

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“…Most of the stressbased fatigue approaches were based on the assumption that load sequence effects are neglected and require the prescription of fatigue loadings, the availability of existing S-N curve database and the determination of stress concentration factor. The fatigue life of a structure under multi-axial loading has been estimated by methods based on principal stress ranges, effective stresses or stress states at different crack planes (Li et al, 2001;Sonsino and Kueppers, 2001;Van Dang et al, 2001;Yousefi et al, 2001). Different from the CFD method, the FCP approach is based on fracture mechanics and can take into account load sequence effects.…”