Fracture analysis of load-carrying cruciform fillet welded joints with multiple cracks

•3-D FE models of load-carrying joints with multiple cracks are generated.•Parametric study is conducted to determine SIFs of these cracks.•The SIF equations at the weld toe and weld root cracks are built up.•The critical crack and weld sizes for the crack propagation are determined. Load-carrying cruciform fillet welded joints configuration is frequently encountered in many welded structures. Different from non-load-carrying joints, the crack in load-carrying joints can propagate from the weld root or from the weld toe. Hence, the crack propagation location is critical for a given weld size, transverse and main plates thickness. In this study, a finite element (FE) mesh generator developed previously is extended to generate 3-D models of load-carrying joints containing cracks at the weld root and the weld toe. Then, extensive parametric study is carried out to calculate the stress intensity factors (SIFs). Corresponding SIF equations are proposed according to multiple regression analysis. Based on these equations obtained for the weld root and weld toe cracks, the critical crack and weld sizes at which the crack propagates from the weld root to the weld toe are determined.