# PSI - Issue 2_A

M Perl et al. / Procedia Structural Integrity 2 (2016) 3625–3646 M. Perl, and M. Steiner / Structural Integrity Procedia 00 (2016) 000–000

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autofrettaged spherical vessel of R 0 /R i =1.2. As a/c increases, the interaction between cracks increases as well. K IAmax in the case of crack density δ≈0.9, is ~3%, ~6%, and ~24% higher relative to its value for δ=0, for crack ellipticities of a/c=0.2, 0.6, and 1.0 respectively.

Fig. 17. K IA /K 0 vs . ψ along the fronts of crescentic coplanar crack arrays of ellipticity a/c=0.2, and densities of δ=0, 0.6, 0.79, 0.89, and 0.95 (a/t=0.1, R 0 /R i =1.2, ε =100%).

Fig. 18. K IA /K 0 vs . ψ along the fronts of lunular coplanar crack arrays of ellipticity a/c=1.0, and densities of δ=0, 0.6, 0.8, and 0.9 (a/t=0.1, R 0 /R i =1.2, ε =100%).

The substantially larger change in K IAmax in the case of the lunular crack also results from the fact that in this case K IAmax occurs around ψ≈ 0°. Moreover, even in a slender crescentic crack array, a/c=0.2, of higher density, δ=0.95 (Fig. 17), the increase in K IAmax is still only ~4%, lower than the increases in the cases of a/c=0.6, and 1.0, for the lower crack density of δ≈0.90. It is worthwhile noting that in the case of a very slender crescentic crack a/c=0.2, the influence of the cusp is so strong that K IAmax shifts to ψ = ψ 0 unlike in the cases with a higher a/c=0.6, and 1.0, where it occurs at the deepest point of the crack, and in the vicinity of ψ≈ 0° respectively.

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