Fatigue strength assessment of the fillet welded cruciform joints

In this study, fatigue tests to obtain S-N curves and FE analyses to obtain structural stress concentration factors were conducted for two types of fillet welded cruciform joints, that is, load-carrying and non load-carrying types. The obtained S-N curve of the load-carrying joint was changed to that based on hot-spot stress. As a result, the S-N curve of the load-carrying joint based on hot-spot stress almost coincided with that of the non load-carrying joint based on nominal stress. The fatigue strength of a welded joint which has a different geometry from that of the non load-carrying cruciform joint but the same bead profile as that of the non load-carrying cruciform joint could be estimated by using both the structural stress concentration factor at the weld toe position obtained from FEM and the nominal S-N curve of the non load-carrying cruciform joint from experiment.