Stress intensity factors for interaction of surface crack and embedded crack in a cylindrical pressure vessel

Abstract

This paper analyzes the interaction of coplanar semi-elliptical surface crack and embedded elliptical crack in a cylindrical pressure vessel. No numerical solution appears to be available in the literature so far for this kind of interaction. The analyzed ratios of the crack depth to crack length are 0.25, 0.5 and 1.0; the distances between two cracks are 0.5, 1.0 and 2.0. In total 54 crack configurations are analyzed and the stress intensity factors along the crack front are presented. The interaction increases the stress intensity factors along the crack fronts for both the surface crack and the embedded one, compared with the single surface crack and single embedded one. And, for the given crack dimensions, the stress intensity factors for both the surface crack and embedded crack increase with the decrease of the distance between two cracks. In the end of the text, an interpolating technique is presented for estimating the stress intensity factors for the interaction of cracks whose ratios of crack depth to crack length are different from 0.25, 0.5 and 1.0. The numerical analyses are carried out by the hybrid boundary element method.