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東 喜三郎*; Li, Y.; 長谷川 邦夫; Shim, D. J.*
Proceedings of 2017 ASME Pressure Vessels and Piping Conference (PVP 2017) (CD-ROM), 7 Pages, 2017/07
Materials made of alloy 82/182/600 used in pressurized water reactors are known to be susceptible to primary water stress corrosion cracking. The depth, , of flaws due to primary water stress corrosion cracking can be larger than the half of crack length , which is referred to as cracks with large aspect ratios. The stress intensity factor solution for cracks plays an important role to predict crack propagation and failure. However, Section XI of the ASME Boiler and Pressure Vessel Code does not provide the solutions for cracks with large aspect ratios. This paper presents the stress intensity factor solutions for circumferential surface cracks with large aspect ratios in cylinders under global bending loads. Finite element solutions were used to fit closed-form equations with influence coefficients gb. The closed-form solutions for coefficient gb were developed at the deepest points and the surface points of the cracks with aspect ratios ranged from 1.0 to 8.0.
東 喜三郎*; Li, Y.; 長谷川 邦夫; Shim, D. J.*
Proceedings of 2016 ASME Pressure Vessels and Piping Conference (PVP 2016) (Internet), 7 Pages, 2016/07
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.