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

The aim of the research described was to establish a sound structural analy sis procedure for load-carrying fillet-welded attachments with particular r eference to cases where the welds are well separated by crack-like disconti nuities. Finite element analysis (FEA) was used to determine linear elastic fracture mechanics stress intensities and limit states for a range of typi cal attachment geometries, on the assumption that these two failure conditi ons represent practical extremes of behaviour. The influence of differences between the yield strengths of the parent materials and the welds was expl ored in the theoretical study. The results of the FEA were analysed to obta in the development of appropriate design/assessment formulae, based on simp le structural mechanics models. These formulae provide an approach that imp roves on current codes of practice, which treat the loads on welds as stati cally determinate and ignore crack-related failure potential. Collapse test s were carried out on two-dimensional models of the cases studied. These in cluded specimens where the strength properties were uniform throughout and others where higher-yield-strength welds were incorporated. The results con firmed the FEA results and associated formula with respect to the limit sta te and provided some insight into the effects of heterogeneous strength pro perties in the junction.