Weight functions and stress intensity factors for internal surface semi-elliptical crack in thick-walled cylinder

Calculation of stress intensity factors for a crack subjected to a complex stress distribution can be highly facilitated by using the weight function method. The method separates influences of a stress held and the geometry of a cracked body on a stress intensity factor. In this paper, mode I weight functions were derived for the deepest and surface points of an internal, radial-longitudinal, surface, semi-elliptical crack in an open-ended, thick-walled cylinder with internal radius to wall thickness ratio R-i/t = 2.0. Generalized weight function expressions for deepest and surface points of the crack were utilized. A method of two reference stress intensity factors was applied to determine coefficients of the weight functions. The weight functions were validated for several crack face stress fields against finite element data. Closed-form relations for calculation of stress intensity factors were obtained for a variety of one-dimensional stress distributions applied to crack faces. The paper complements a set of previously published weight function solutions for cracks in cylinders with other radius to thickness ratios. (C) 1997 Elsevier Science Ltd.