Reliability of welded structures containing cracks in heat-affected zones

This study investigates the reliability of plate containing a semi-elliptic al surface crack intersecting regions of dissimilar material properties. A weakest-link model is developed to express fracture toughness distributions in terms of effective crack lengths that account for the varying stress in tensity factor along the crack front. The model is intended to aid in the d evelopment of fracture toughness distributions for cracks encountering loca l brittle zones (LBZ) in the heat-affected zones (HAZ) of welded joints, wh ere lower-bound fracture toughness values have been measured in the laborat ory when a significant portion of the crack front is intersecting the coars e-grained LBZs. An example reliability analysis is presented for a surface crack in a material containing alternating bands of two Weibull-distributed toughnesses.