PSI - Issue 21

Hakan Şahin et al. / Procedia Structural Integrity 21 (2019) 38–45 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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(a)

(b)

(c) Figure 6: Normalized mode III stress intensity factors for inclined surface cracks a/t =0.4, (a) a/c =0.25; (b) a/c =1.0, (c) a/c =4.0.

Fig. 6 shows the normalized mode-III SIFs distributions. Similar to mode-II, the highest values are obtained at 45 degree inclination angle with respect to the horizontal axis. The same mode-III SIFs obtained for surface cracks in 15 75 and 30-60 degrees, which complement each other to 90 degrees. It’s clear that, n ormalized K 3 values show a symmetrical distribution on graph. It is noted that in the very near vicinity of the point where the crack front intersects the free-surface, the type of strain singularity is different than the classical r -1/2 and that no special mesh or formulation treatments are made in this study to capture the “true” SIF distributions in this very localized region. Finally, from the results presented it is observed that although the remote loading is uniaxial tension (mode-I), due to the shear stress acting in the inclined plane of the crack, all modes of fracture, with coupled mode-II and – III SIFs, are observed. Coupling of modes-II and – III was also observed previously. See, for example, Pook et al. (2015).