Issue 49

G. Meneghetti et alii, Frattura ed Integrità Strutturale, 49 (2019) 53-64; DOI: 10.3221/IGF-ESIS.49.06 58    Figure 4 : Averaged SED evaluated according to the nodal stress (NS) approach (Eqn. (17)); (a) and (c) geometry and loading conditions. Coarsest FE mesh to obtain a reduced error of 10% in the cases: (b) in-plane mixed mode I+II crack problem with 2a = 3 mm and MM = 0.50 and (d) out-of-plane mixed mode I+III crack problem for any mode mixity ratio MM and crack length a. T HE P EAK S TRESS M ETHOD TO RAPIDLY EVALUATE K I , K II AND K III he Peak Stress Method (PSM) is an approximate numerical technique to evaluate the SIFs. The PSM takes its origins by a numerical technique proposed by Nisitani and Teranishi [17] to rapidly estimate by FEM the mode I SIF of a crack emanating from an ellipsoidal cavity. A theoretical justification to the PSM has been provided later on and the method has been extended also to sharp and open V-notches in order to rapidly evaluate the mode I Notch Stress Intensity Factor (NSIF) [18]. Subsequently, the PSM has been formalised to include also cracked components under mode II loading conditions [19] and open V-notches subjected to pure mode III (anti-plane) stresses [20]. T σ nom τ nom 2a = 3 mm W = 10 ·2a L = W σ yy,peak τ xy,peak (a) τ nom y x r θ (b) d ≅ 0.15 mm crack tip a D = 10 ·a L = D (c) M t a 2α=0° M t F F r θ y x z σ yy,peak σ yy,peak τ yz,peak τ yz,peak d = a/3 (d) a crack tip