Issue 35

S S. El Kabir et alii, Frattura ed Integrità Strutturale, 35 (2016) 64-73; DOI: 10.3221/IGF-ESIS.35.08 70 show stable crack growth zones for 2 sizes. The results are summarized in Table 1 where different new size parameters are given versus stable crack growth zones. Fig. 8 (a) illustrates the evolution of the energy release rate versus the crack length for several MMCG specimen thicknesses b and size a=1 . G 1 and G 2 are the parts of opening and shear in the mixed mode 45°. We observe that the values of G increase when the thickness decreases. Stable crack growth zones are also presented in Fig. 8 (b) and (c). Figure 7 : Normalized elastic energy release rate G1 and G2 versus mixed mode ratio for various sizes parameter 3 1 3 1 1; ; and b 1 (a), for and 1 (b), for and 1(c) 4 2 4 2 a a b a b             . Size parameter a Stable zone G1 (mm) Length of stable zone G1 (mm) Stable zone G2 (mm) Length of stable zone G2 (mm) 1 [54:82] 28 [93:114] 21 0.75 [40.5:61.5] 21 [69.75:85.5] 15.75 0.5 [27:41] 14 [46.5:57] 10.5 0.25 [13.5:20.5] 7 [23.25:28.5] 5.25 Table 1 : Stable crack growth zones for different size parameter and 1 b  .