PSI - Issue 47

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Hachimi Taoufik et al. / Procedia Structural Integrity 47 (2023) 711 – 722 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

Fig. 12. Normalized crack length as a function of life fraction.

In other words, the sudden propagation of the crack results from the increase in SIF. This increase is plotted in Fig. 13, which depicts the evolution of the stress intensity factor KI as a function of the crack length a/w. The SIFs are calculated by the empirical formula of equation (4). Three zones of generalized behavior can be identified in the fracture growth curve. In the threshold region, crack growth is slow as KI is asymptotically close to a threshold value of KI, where Crack growth might not occur. The curve shape of the crack growth is approximately linear in the intermediate zone. And the unstable area is characterized by the rapidity of crack change where the failure of the structure is imminent. 45°/-45°

150

Modeling Experimental

100

50 KI (Mpa√m)

0

0.2

0.4

0.6

0.8

1.0

a/w

Fig. 13. Stress intensity factor as a function of crack length.