Issue 36

R. H. Talemi, Frattura ed Integrità Strutturale, 36 (2016) 151-159; DOI: 10.3221/IGF-ESIS.36.15 158 where a is the crack length,  is the span-to-width ratio ( WS /   , shown in Fig. 2),  is the crack-to-width ratio ( Wa /   , and 1 ( ) C  and ) ( 2  C are non-dimensional functions depending on  and  values that can be found in Guinea et al. [12]. For the geometry considered in the present work these functions can be written as:         2 3 1 1.5 1.9 0.41 0.51 0.17 1 1 3 C              (13)     2 3 2 2 0.66 0.76 2.28 3.87 2.04 1 C            (14) Fig. 5(a) illustrates the propagated crack through single mesh and the measured δ CMOD of the DWTT model. Fig. 5(b) shows the variation of calculated dynamic stress intensity factor versus δ CMOD . As it can be noticed the relationship between the stress intensity in dynamic mode is linear with the δ CMOD . ߜ ஼ெை஽ ܽሶ 0 50 100 150 200 0 0.5 1 1.5 2 ܭ ூ஽ [MPa ݉ ] ߜ ஼ெை஽ [mm] (a) (b) Figure 5 : (a) propagating crack through single mesh of DWTT model and (b) calculated dynamic stress intensity factor versus Crack Mouth Opening Distance (δ CMOD ). 10 2 10 3 0 0.1 0.2 0.3 0.4 0.5 ܽሶ [m/s] ௄ ಺ವ ఙ ೤ గ௔ [‐] ܽሶ ൌ ܿ ଵ ݈݊ ܭ ூ஽ ߪ ௬ ܽ ൅ ܿ ଶ Figure 6 : Calculated crack velocity versus normalized crack tip dynamic stress intensity factor. Fig. 6 presents the variation of the measured crack propagation speed versus the normalized dynamic stress intensity factor calculated using Eq. 12. As it is shown in the figure the relationship between the crack propagation speed and the