Issue 49

B. G. N. Muthanna et alii, Frattura ed Integrità Strutturale, 49 (2019) 463-477; DOI: 10.3221/IGF-ESIS.49.44 469 (a) (b) (c) Figure 8: Stresses distribution in elbow (a) Von-Mises stress, (b) Normal stress  xx and (c) Principal stress   (a) (b) (c) Figure 9: Maximum stresses distribution versus crack angle  in elbow (a) Von-Mises stress, (b) Normal stress  xx and (c) Principal stress     The original point of cracking at critical zone is one of among important reasons responsible for pipe elbow corrosion issue. Fig. 10 presents the stress intensity factor distributions in a semi-elliptical surface crack for different angular positions  along the elbow intrados surface  . Maximum mode I stress intensity factor K I,max is localized at  =75° and is given by the following formulae [33-36] :