Stress-intensity-factor influence coefficients for semielliptical inner-surface flaws in clad pressure vessels

A problem of particular interest in pressure vessel technology is the calculation of accurate stress-intensity factors for semielliptical surface cracks in cylinders. Computing costs for direct solution techniques can be prohibitive when applied to three-dimensional (3-D) geometries with time-varying boundary conditions such as those associated with pressurized thermal shock. An alternative superposition technique requires the calculation of a set of influence coefficients for a given 3-D crack model that can be superimposed to obtain mode-I stress-intensity factors. This paper presents stress-intensity-factor influence coefficients (SIFICs) for axially and circumferentially oriented finite-length semielliptical inner-surface flaws with aspect ratios [total crack length (2c) to crack depth (a)] of 2, 6, and 10 for clad cylinders having an internal radius (R{sub i}) to wall thickness (t) ratio of 10. SEFICs are computed for flaw depths in the range of 0.01 {le} a/t {le} 0.5 and two cladding thicknesses. The incorporation of this SEFIC data base in fracture mechanics codes will facilitate the generation of fracture mechanics solutions for a wide range of flaw geometries as may be required in structural integrity assessments of pressurized-water and boiling-water reactors