Structural integrity of a welded attachment junction: Analysis and collapse tests

The aim of the research described was to establish a sound structural analysis procedure for load-carrying fillet-welded attachments with particular reference to cases where the welds are well separated by crack-like discontinuities. Finite element analysis (FEA) was used to determine linear elastic fracture mechanics stress intensities and limit states for a range of typical attachment geometries, on the assumption that these two failure conditions represent practical extremes of behaviour. The influence of differences between the yield strengths of the parent materials and the welds was explored in the theoretical study. The results of the FEA were analysed to obtain the development of appropriate design/assessment formulae, based on simple structural mechanics models. These formulae provide an approach that improves on current codes of practice, which treat the loads on welds as statically determinate and ignore crack-related failure potential. Collapse tests were carried out on two-dimensional models of the cases studied. These included specimens where the strength properties were uniform throughout and others where higher-yield-strength welds were incorporated. The results confirmed the FEA results and associated formula with respect to the limit state and provided some insight into the effects of heterogeneous strength properties in the junction.