Issue 31

A.R. Maligno et alii, Frattura ed Integrità Strutturale, 31 (2015) 97-119; DOI: 10.3221/IGF-ESIS.31.08 111 the compressive zone at the pipe’s cross-section the stress intensity started dropping. This phenomenon was further studied and it is explained in Analytical Study: Stage 2 . (a) (b) (c) (d) (e) (f) Figure 20: Multi-step procedure at Stage 2: (a) initial through-the-thickness crack; (b) crack configuration at end of Step 1 (TW 1); (c) crack configuration at end of Step 2 (TW 2); (d) crack configuration Step 3 (TW 3); (e) crack configuration Step 4 (TW 4); (f) crack configuration at Step 5 (TW 5). Figure 21 : Comparison of overall K curves for internal and external surface nodes.