3-DIMENSIONAL INTERACTION EFFECTS IN AN INTERNALLY MULTICRACKED PRESSURIZED THICK-WALLED CYLINDER .2. LONGITUDINAL COPLANAR CRACK ARRAYS

In the first part of this paper, the interaction effects among many ra dial, internal, semi-circular, and semi-elliptical cracks in a pressur ized, thick-walled vessel were quantified, In the present paper, the m ode I stress intensity factor (SIF) distribution for numerous longitud inal coplanar internal, semi-circular, and semi-elliptical arrays of s urface cracks in mt infinite, pressurized, thick-walled cylinder are e valuated. The 3-D analysis is performed by the finite element (FE) met hod and the submodeling technique, employing singular elements along t he crack front. The effects of dense and sparse interacting longitudin al coplanar crack arrays on the SIFs are studied for a wide range of c rack depth to wall thickness ratios, a/t, from 0.05 to 0.6; and for va rious ellipticities of the crack, i.e., the ratio of the crack depth t o semi-crack length, a/c, from 0.2 to 2.0. An analysis is performed to determine the influence of the three major parameters -crack density crack ellipticity, and crack depth-on the interaction effects between adjacent cracks. The results clearly indicate that crack density, and, in some cases, ellipticty have opposing effects on the SIF of longitu dinal crack arrays as compared to radial crack arrays. As a result of these contrasting behaviors, thick-walled cylinders having contained l ongitudinal and radial crack would need further study.