Issue 35

O. Demir et alii, Frattura ed Integrità Strutturale, 35 (2016) 340-349; DOI: 10.3221/IGF-ESIS.35.39 346 Specimen No Loading Angle (°) CRITICAL LOAD VALUES (kN) Richard [10] Erdogan and Sih [1] Pook [8] Tanaka [9] Developed Criterion Experimental Results T-LT-01-251214-01 0 21.01 21.01 21.01 21.01 - 19.60 T-LT-01-180115-12 15 20.21 20.19 20.20 20.36 19.67 19.80 T-LT-01-180115-13 15 20.46 20.44 20.44 20.60 19.92 19.70 T-LT-01-180115-14 30 22.22 22.15 22.16 22.81 21.24 23.07 T-LT-01-180115-15 30 21.88 21.82 21.82 22.51 20.88 20.64 T-LT-01-251214-02 45 27.05 26.86 26.86 29.01 25.87 28.09 T-LT-01-251214-03 45 26.75 26.56 26.56 28.62 25.56 29.21 T-LT-01-251214-04 60 30.89 30.50 30.49 35.10 30.98 33.59 T-LT-01-090215-18 60 32.20 31.81 31.81 36.46 32.06 34.76 T-LT-01-180115-17 75 43.93 43.24 43.19 46.07 52.14 54.31 T-LT-01-220215-22 75 43.97 43.29 43.23 45.89 52.50 55.04 Table 5 : Experimental and predicted T-specimen fracture loads obtained from the developed criterion along with other existing criteria in the literature. Figure 2 : Comparisons of experimental and predicted T-specimen fracture load values. Comparisons of Mode-I/II Fracture Criteria In Terms of Crack Deflection Angle In this subsection, the predicted crack deflection angles from the developed criterion are compared with other existing criteria in the literature. In an effort to develop an improved empirical mode-I/II crack deflection angle equation, mixed mode SIFs obtained from detailed finite element models of CTS and T-specimen and crack deflection angles obtained from the experiments for different loading angles are used. Developed crack deflection angle equation is given by: 2 3 4 5 2 3 4 5 0 ln( ) ln( ) ln( ) ln( ) ln( ) I I I I I II II II II II a b K c K d K e K f K gK hK iK jK kK             (13) 0° loading case data is excluded as is the case with the development of equivalent SIF equation to develop the improved in-plane mixed mode-I/II crack deflection angle equation. Coefficients in Eq. (13) are given in Tab. 6. a b c d e f g h i j k -0.7907 2.0365 -3.4144 2.2844 -0.5928 0.0465 1.1736 -2.6539 1.8244 -0.5330 0.0565 Table 6 : Coefficients of developed crack deflection angle equation.