3-D stress intensity factors due to full autofrettage for inner radial or coplanar crack arrays and ring cracks in a spherical pressure vessel

• SIFs for radial and coplanar crack arrays, and ring cracks in a spherical vessel.
• Effect of the number of cracks/crack density on the SIFs in radial/coplanar arrays.
• The influence of crack ellipticity and depth, and the vessel’s geometry on the SIFs.
• The importance of the autofrettage model employed including the Bauschinger effect.
• Comparison between arrays of coplanar cracks and a ring crack.

Three dimensional, stress intensity factor for inner radial or coplanar crack arrays and ring cracks prevailing in an autofrettaged spherical pressure vessel are evaluated. The 3-D analysis is performed via the finite element method implementing a novel realistic autofrettage residual stress field incorporating the Bauschinger effect. SIFs are evaluated for arrays of radial or coplanar cracks and ring cracks of depth to wall thickness ratios of a/t = 0.1–0.6, and ellipticities of a/c = 0.2–1.0 in fully autofrettaged spherical vessels, ε = 100%, of Ro/Ri=1.1,1.2, and 1.7. SIFs are evaluated for radial arrays containing n = 1–20 cracks, and for arrays of coplanar cracks of δ = 0–0.95 densities.