PSI - Issue 42

Abdulla Abakarov et al. / Procedia Structural Integrity 42 (2022) 1046–1053 A. Abakarov and Y. Pronina / Structural Integrity Procedia 00 (2019) 000–000

1049

4

a

b

c

d

Fig. 4. Comparative analysis for di ff erent cracks configurations. (a) SBS; (b) BSB; (c) BSBSB; (d) BS44p.

mode I SIFs are. The more interesting thing, however, is that the dependencies of the SIFs for the central big cracks in the arrays consisting of five cracks and in periodic arrays turned out to be qualitatively di ff erent for relatively small distances between the cracks (compare three lowest lines in Fig. 4c and 4d). This graph (Fig. 4c) was expected to be somewhat intermediate between the neighboring configurations. And it really is for the large distances between the cracks, but not for the relatively small. This surprising observation may be explained by the fact that the interaction between small and big cracks is suppressed by the interaction between only big cracks at small distances between them. The above conclusion is confirmed by the graphs in Fig. 5, where the final (i.e. at t ∗ = 150 hours) relative mode I SIFs are presented for the same configurations as observed above but without small cracks. The central crack lying between the two others (configuration BBB) has the lowest mode I SIF and thus grows slowly compared to its neigh bors, so that its SIF decreases due to shielding e ff ect from its neighbors. And when its neighbors’ length becomes relatively large, the SIF of the central crack becomes less than the threshold value K SCC I , which leads to the cessation of the central crack growth. In the process of further growth of the side cracks, the SIF of the central one becomes even negative. In infinite periodic arrays, all the cracks of the same initial length grow at equal rates and thus have equal lengths at any time. 4.2. Interaction of big cracks with one another

4.3. The e ff ect of small cracks on big ones

To separate the e ff ect of small cracks on big ones from the e ff ect of interaction of big cracks with one another, we considered the data for the big cracks at t ∗ = 150 hours in configurations containing both big and small cracks,