PSI - Issue 37

Jesús Toribio et al. / Procedia Structural Integrity 37 (2022) 989–994 Jesús Toribio / Procedia Structural Integrity 00 (2021) 000 – 000

992 4

3. Numerical results Fig. 4 shows the dimensionless SIF K I / σ ( π D )

1/2 along the crack front (characterizing its points by means of the angle θ ) for d / D =0.4 and for ε / D from 0 (symmetric case) to 0.200 with increments of 0.025 and Fig. 5 the axial displacement u z on the deformed profile (showing the initial profile in black color).

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0 30 60 90 120 150 180  (º) A B K I /  (  D) 1/2  /D A B 

Fig. 4. Dimensionless SIF along the crack front for d / D =0.4 and ε / D from 0 to 0.200 with increments of 0.025.

(a)

(b)

(c)

(d)

Fig. 5. Displacement u z for d / D =0.4: (a) ε / D =0; (b) ε / D =0.025; (c) ε / D =0.050; (d) ε / D =0.125.

For non-symmetric cracks, the eccentricity of the resistant ligament makes the SIF vary along the crack front, increasing from point B to point A. The increase of eccentricity raises the differences between SIFs at different points of the crack, thereby increasing even more the eccentricity itself when the cracks propagate by subcritical mechanisms of propagation such as fatigue or SCC. The tensile loading applied at the bar ends generates a bending stress caused by the eccentricity of the ligament, thus provoking a rotation in the sample. From ε / D =0.050 (Fig. 5c) partial contact appears between the crack faces, thereby reducing the trend of SIF increment with the eccentricity and for ε / D =0.125 (Fig. 5d) full contact takes place, so that the crack remains fully closed in the zone associated with the tip B (where the SIF is equal to zero).