PSI - Issue 2_A

L.R. Botvina et al. / Procedia Structural Integrity 2 (2016) 373–380 L.R. Botvina/ Structural Integrity Procedia 00 (2016) 000–000

378

6

a

b

c

d

e

Fig. 2. (a, b) dependences of the cumulative mass of shell fragments from steel 60 on the length with a diameter of 20, 4 (1) 34, 2 (2) and 48, 1 (3) mm in ordinary (a), the logarithmic (b) and (c) the relative coordinates; (d) the cumulative mass - length distribution of the fragment, proposed by Grady (2010) and (e) the modified Schuhmann’s scheme for shells of different diameters This transition is caused by the change of the fragmentation mechanism that occurs at the points marked by arrow in Fig. 2a, b, and their corresponding point T shown in the diagram (Fig. 2e) that divides the diagram into two parts of the stable (II a) and fast (II b) change of mass at reaching the fragment length λ 2 accompanied by increasing thickness and fragments lengths. Such sections of stable and accelerated growth of the cracks were selected also on the diagram of fatigue crack development by Ritchie and Knott (1973).