Fatigue crack growth in cruciform welded joints: Influence of residual stresses and of the weld toe geometry

The aim of the present investigation is to calculate the fatigue life of cruciform welded joints by taking into account both the effect of residual stresses and the influence of the weld toe geometry. Two and three dimensional finite element models, with cracks as initial defects, will be constructed for this purpose. Fatigue crack growth analyses are performed by using the node release technique, together with the finite element program ABAQUS. The welding residual stresses, as well as the plasticity induced crack closure effects, are considered. The effective cyclic J-integral (ΔJeff) is used as crack tip parameter in a relation similar to the Paris equation for the calculation of the fatigue life. For this purpose, a specific code was written for the determination of ΔJeff at each crack length configuration. The impact of residual stresses on ΔJeff as well as on the fatigue life during short crack growth is investigated. Results reveal that the influence of residual stresses can be neglected only for large load amplitudes. The calculated fatigue lives are compared with experimental data and a good accordance between both results is achieved. The influences of the weld toe radius and of the weld flank angle are also investigated.