Erosion geometry effects on the stress intensity factors of a crack emanating from an erosion in an autofrettaged pressurized thick-wall cylinder

Erosion geometry effects on the mode I stress intensity factor (SIF) for a crack emanating from an erosion's deepest point in an autofrettaged, pressurized, thick-walled cylinder are investigated. The problem is solved via the FEM method and knowledge of the asymptotic behavior of short cracks. Autofrettage, based on von Mises yield criterion, is simulated by thermal loading and SIFs are determined by the nodal displacement method. SIFs are evaluated for a variety of relative crack lengths, a_σ/W = 0.01 - 0.45 emanating from the tip of erosions of different geometries, namely, a) semi-circular erosions of relative depths of 1-10% of the cylinder's wall thickness, W; b) arc erosions for several dimensionless radii of curvature, r'/W = 0.05 - 0.4; and c) semi-elliptical erosions with ellipticities of d/h = 0.3 - 2.0, While deep cracks are almost unaffected by the erosion, the effective SIF for relatively short cracks is found to be considerably enhanced by the presence and geometry of the erosion that may result in a significant decrease in the vessel's fatigue life of up to an order of magnitude.