Stress Intensity Factors for Fatigue Cracks at the Toe of a Transverse Weld.

The purpose of this paper is to explore the validity of existing solutions for the stress intensity factor K, in order to determine this factor in the case of fatigue cracks initiated at the toe of a transverse weld. It is shown first that, depending on the configuration of the cracks in the plate cross section, they can be idealized by semielliptical surface cracks, quarter-elliptical corner cracks and straight-front through cracks. A critical review of the existing K//I solutions for cracks at the toe of a transverse welded joint is presented. It is shown that the use of correction factors to take into account a curvilinear crack front is invalid. Recent results reported for semielliptical and quarter-elliptical cracks are discussed. All these solutions concern plates of constant thickness, however; therefore they are not directly applicable to cracks propagating from notches. It is concluded that the most important task for obtaining a correct estimate of the stress intensity factors for cracks in welded joints is to study problems of stress intensity factors for curved front cracks emanating from notches.