Issue 47

L. Marsavina et al., Frattura ed Integrità Strutturale, 47 (2019) 266-276; DOI: 10.3221/IGF-ESIS.47.20 270 2 2 eff I II K K K   (5) Tab. 2 presents the specimen dimensions, maximum load, the mode I, mode II and effective SIFs. A higher value of K eff = 0.785 MPa·m 1/2 was obtained for the PB with 25 mm thickness comparing with the PB of 16 mm thickness, K eff = 0.631 MPa·m 1/2 . a. Single Edge Notch Bend b. Compact Shear Figure 4 : Test specimens for mode I and mode II fracture toughness determination. Specimen B [mm] W [mm] H [mm] a [mm] F max [N] K I [MPa·m 1/2 ] K II [MPa·m 1/2 ] K eff [MPa·m 1/2 ] Mean K eff [MPa·m 1/2 ] II.1 16.4 50.3 76.6 25.0 3110 0.101 0.565 0.574 0.631 II.2 16.4 50.0 76.0 25.0 3470 0.113 0.630 0.640 II.3 16.4 51.1 76.0 25.0 3700 0.120 0.672 0.682 II.4 16.4 49.3 76.3 25.6 3050 0.091 0.532 0.540 II.5 16.4 50.0 76.0 25.0 3900 0.127 0.708 0.720 II.6 24 75.0 100 48.5 5911 0.198 0.826 0.850 0.785 II.7 24 76.0 100 48.5 5189 0.174 0.725 0.746 II.8 24 76.2 100 49.2 5788 0.194 0.810 0.833 II.9 24 75.0 100 48.7 5587 0.187 0.781 0.803 II.10 24 75.4 100 47.7 4814 0.162 0.674 0.693 Table 2 : Mode II fracture toughness results The obtained results are represented in the fracture envelope plot K II /K IC versus K I /K IC side by side with the analytical predictions of Maximum Tensile Stress (MTS) [45, 46], Maximum Energy Release Rate (Gmax) [47, 48] and Minimum Strain Energy Density (SED) [49, 50]. From Fig. 5, it could be observed that the MTS and SED criteria fits better with the experimental results.