PSI - Issue 42

Shiwen Wang et al. / Procedia Structural Integrity 42 (2022) 441–448 Shiwen Wang, Paul A Shard , Antony M Hurst and Yueb o Lei / Structural Integrity Procedia 00 (2019) 000 – 000

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(a)

(b)

Fig. 7

Location of Maximum J; (a) elastic; (b) elastic plastic (n=5)

4. Discussion The results in previous section show that the R6 option 1 & 2 curves are found not to be conservative for very deep cracks with high aspect ratio (a/c=0.2, a/t=0.8) and at some through thickness bending ratios. The reason for these results will be discussed in relation to the location of maximum elastic J, J el , due to: 1) crack depth; and 2) through thickness bending ratio,  will be investigated: 4.1. Effect of Crack Depth for crack of aspect ratio a/c=0.2 The distribution of J around the crack front for a high aspect ratio crack (a/c=0.2) at different depths (a/t=0.2, 0.5, 0.8) are shown in Figure. 7 for elastic and elastic plastic (n=5) cases. At shallow to medium depth (a/t=0.2, 0.5), the maximum J is located at the deepest point on the crack front ( = /2) for both the elastic and elastic plastic model. For a deep crack (a/t=0.8), the maximum J moves to locations between surface and deepest point, the location for the maximum J between elastic and elastic-plastic models is also different.

(a) shallow depth (a/t=0.2)

(b) deep depth (a/t=0.8)

Fig. 8

Effect of through thickness bending upon distribution of elastic J

4.2. Effect of Through Thickness Bending (  =0.0, 0.2, 0.5, 1.0, 2.0) The effect of through thickness bending, in terms of  , upon elastic J distribution around the crack front has been investigated for a crack of aspect ratio a/c=0.2 at two depths: (a) shallow depth (a/t=0.2) and deep depth (a/t=0.8).