Issue 47

L. Marsavina et al., Frattura ed Integrità Strutturale, 47 (2019) 266-276; DOI: 10.3221/IGF-ESIS.47.20

2

2

eff II K K K   I

(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.

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 ]

Specimen

II.1 II.2 II.3 II.4 II.5 II.6 II.7 II.8 II.9

16.4 16.4 16.4 16.4 16.4

50.3 50.0 51.1 49.3 50.0 75.0 76.0 76.2 75.0 75.4

76.6 76.0 76.0 76.3 76.0 100 100 100 100 100

25.0 25.0 25.0 25.6 25.0 48.5 48.5 49.2 48.7 47.7

3110 3470 3700 3050 3900 5911 5189 5788 5587 4814

0.101 0.113 0.120 0.091 0.127 0.198 0.174 0.194 0.187 0.162

0.565 0.630 0.672 0.532 0.708 0.826 0.725 0.810 0.781 0.674

0.574 0.640 0.682 0.540 0.720 0.850 0.746 0.833 0.803 0.693

0.631

24 24 24 24 24

0.785

II.10

Table 2 : Mode II fracture toughness results

The obtained results are represented in the fracture envelope plot K II /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. versus K I /K IC

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