Issue 49

H. Chbani et alii, Frattura ed Integrità Strutturale, 49 (2019) 763-774; DOI: 10.3221/IGF-ESIS.49.68 771 Fig. 12 demonstrates the evolution of Δac as function of notch length. Therefore, we may observe that crack propagation decreases almost linearly and disproportionately with a 0 . Figure 13: K R curve as function of Δa for various notch lengths a) a0=30 mm, b) a0=40mm, c) a0=50mm and d) a0=60mm It was demonstrated that the crack propagation zone does not exceed 90 mm for the various initial notches a 0 [20]. For our case, this is means that the specimen failure occur at α max = 0.9 (Fig. 14). Figure 14: Representation of the crack propagation zone [15] The critical stress intensity factor K IC corresponding to Δa c and P max is respectively equal to 1.18, 1.02, 1.01, and 1.01 MPa.m 1/2 for a 0 = 30, 40.50, and 60 mm (Fig.. 14). From the found results, K IC has an average value of 1.05 MPa.m 1/2 and a standard deviation of 0.04 MPa.m 1/2 .