Fitness-for-Service codes require whether non-aligned cracks be treated as coalesced or separate multiple cracks. The authors previously reported on the effect between an corner and an embedded parallel crack in 2-D and in 3-D scenarios subject to tensile loading. Since realistic crack configurations detected using non-destructive methods are generally 3-D in nature, the study of 3-D effect under different loading types is deemed necessary in order to obtain more practical guidance. In this study, we investigate stress intensity factors (SIFs) along the crack front of a quarter-circle corner crack when affected by a semi-elliptic surface crack in a semi-infinite large solid under pure bending. While keeping constant the geometry of the quarter-circle corner crack, the SIFs along its front are studied for a wide range of geometrical configurations of the surface crack by varying its ellipticity b1/a1 = 0.1∼1; the relative crack size of the two parallel cracks a1/a2 = 1/3∼2; the normalized vertical gap, H/a2 = 0.4∼2; and the normalized horizontal gap, S/a2 = −0.5∼2 between the two cracks on using linear elastic fracture mechanics (LEFM). The results from this study are collectively significant to the understanding of the correlation between the criteria and standards in Fitness-for-Service community and the consequence of their usage in engineering practice.

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