PSI - Issue 71

Akash Shit et al. / Procedia Structural Integrity 71 (2025) 50–57

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subjected to a remote stress σ, as shown in Fig. 4 (a), and (b) is given by [Pilkey, (2005)] — = √ ( ) Here a is the half-crack length and the geometric factor, ( ) is — ( ) = [1 − 0.1 ( ) 2 + 0.96 ( ) 4 √ ]

(6)

(7)

Compared to the theoretical results, the deviation of the FEA results was less than 4%, as shown in Table 1. For higher crack lengths, less error is obtained. Table 1. Theoretical validation of mesh parameters Crack length (2a), mm KI (Theoretical), √ KI (FEA), √ % error w.r.t. theoretical 6 247.06 255.9 3.58 8 286.62 296.5 3.48 10 322.40 332.8 3.23 12 355.83 366.2 2.91 3. Results and Discussions The percentage change of SIF from plane perpendicular assumptions is studied to find the influence of MERR based crack advancement on SIF for three interference levels across four different hole locations. The deviation of crack path angle and interference effect on crack path deviation is studied for the H4 and H5 holes of the most critical row, R3. 3.1. Impact of MERR-Based Crack Advancement on SIF with No Interference The SIF at H1, H2, H4, and H5 locations without interference is calculated by extending the crack according to the MEER approach. Fig. 5(a) shows the variation of SIF with crack length under MERR based crack advancement and plane perpendicular assumption quoted in the literature [Hithendra and Prakash, (2021)] for H1 and H2. And Fig. 5(b) shows the percentage difference of SIF along crack length w.r.t the plane perpendicular crack path. At H1, the SIF value is more than the literature, and the percentage difference increases with the crack length. The maximum percentage difference of 152% was found for 12 mm crack length. Whereas at H2, for the initial 6mm crack length, the value of SIF is obtained less than the literature because mixed mode fracture happened due to the initial crack orientation, and the mode-II SIF precedes the mode-I SIF. After that, the SIF value obtained more than the literature for further crack lengths. However, compared to H4 and H5, the SIF at H2 and H1 is significantly less. With crack length, the SIF values decreased for H2 and remained almost the same for H1, as mentioned in other literature [Hithendra and Prakash, (2021)]. a b

Fig. 5. H1 and H2 under 0% interference (a) Variation of SIF with crack length (b) % change in SIF w.r.t. the plane’s perpend icular crack propagation