Reference stress based J estimation formula for cracked cylinders with a wide range of radius-to thickness ratios: Part II- circumferential surface cracks

In this paper, reference stress based J estimation equations are presented for circumferential constant-depth surface and through-wall cracked cylinders with the radius to thickness ratio ranging from three up to seventy. The equations are developed based on extensive finite element (FE) analysis results. Firstly it is shown that application of existing J estimation equations is limited to thick-walled cylinder problems and can give non-conservative J estimates for a cylinder with a large radius-thickness ratio. To accommodate the effects of the crack depth, length and the radius-to-thickness ratio, correction factors for the reference stress are proposed based on FE results. By comparing with FE results, it shows that the proposed solutions can be applied to both an external and internal crack; and to combined axial tension and global bending.