Mixed Mode Stress Intensity Factors for a Slanted Edge Crack Under Remote Uniform Tension Affected by an Adjacent Horizontal Crack

Abstract

Fracture mechanics has been used in Fitness-for-Service (FFS) assessments of structures containing cracks. The stress intensity factors (SIFs) at the crack tip are the key information in assessing the remaining service life of a cracked component. Extensive studies have been carried out on the mutual influence of adjacent parallel cracks. However, to date no solutions are available for nonparallel cracks. In the present analysis mode I (KI) and Mode II (KII) SIFs of a slanted-edge-crack affected by an adjacent nonparallel horizontal crack are obtained. KI and KII are evaluated for a wide range of the slanted edge crack angle β = 0 deg–70 deg, for various normalized horizontal (S/a2 = −0.4 to 2) and vertical (H/a2 = 0.4 and 2) separation distances and for several crack lengths. The problem is solved using a two-dimensional, plane strain, finite element model, which was successfully validated against presently available solutions. It is found that the presence of the horizontal crack always amplifies KI of the edge crack while KII might be either amplified or attenuated depending on the crack configuration. Furthermore, the present results indicate that, for the purpose of Fitness-for-Service, the effective SIF at the tip of the slanted crack always increases due to the presence of the horizontal crack.