Stress intensity factor solutions for circumferential surface cracks with large aspect ratios in pipes subjected to global bending

グローバル曲げに作用された配管における表面周方向高アスペクト亀裂の応力拡大係数について

東 喜三郎*; Li, Y. ; 長谷川 邦夫; Shim, D. J.*

Azuma, Kisaburo*; Li, Y.; Hasegawa, Kunio; Shim, D. J.*

In some cracks attributed to primary water stress corrosion cracking, the crack depth a was greater than half-length of the crack 0.5, namely, cracks with large aspect ratio a/. This paper presents details of stress intensity factor solutions for circumferential surface cracks with large aspect ratios in piping system subjected to global bending. The stress intensity factor solutions for semi-elliptical surface cracks were obtained by finite element analyses with quadratic hexahedron elements. Solutions at the deepest and the surface points of the cracks with various aspect ratio (0.5 a/ 4.0), crack depth ratio (0.0 a/t 0.8) and pipe sizes (1/80 t/R 1/2) were investigated, where t and R are wall thickness and inner radius of pipe, respectively. Proposed stress intensity factor solutions for cracks with a/ = 0.5 are consistent with the values reported in the previous study. The solutions developed in this study are widely applicable to various engineering problems related to crack evaluation in piping systems.