Crack behavior in a residual stress field at fillet welds in ship structure

Fillet welds are used in joining longitudinal stiffeners in ship structures. Welding residual stresses in fillet welds are generally distributed in a non-uniform manner. As the residual stress influences the crack propagation originating from the toe of the fillet welds, a full understanding of the residual stress field and how it evolves is very important for structural integrity calculations. Previous work was aimed at determining the residual stress redistribution under cyclic loading in the elastic shakedown regime. However, that work did not consider the presence of any flaw or defect: knowledge of the residual stress redistribution in the presence of a flaw is therefore required for better fatigue life prediction. Moreover, defect assessment procedures such as BS7910 offer very limited guidance for flaw acceptance and the associated residual stress redistribution in the assessment of fillet welds. Therefore, the objective of this work is to study the effect of a surface-breaking flaw at the weld toe region in a fillet weld under cyclic load to determine the residual stress evolution at pre-defined crack depths.