PSI - Issue 39

Hithendra Karakampalle et al. / Procedia Structural Integrity 39 (2022) 711–721 Author name / Structural Integrity Procedia 00 (2021) 000–000

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Fig. 7 Typical mesh

3. Results and Discussion 3.1. Case 1:

SIFs are different at the two crack tips – top (Tip 1) and bottom (Tip 2). Variation of SIFs at crack tips 1 and 2 at 0% interference level can be seen in the Fig. 8. The two discontinuities in the SIF plot at tip 1 are due to the presence of rivet holes between 16 mm - 22mm and 31mm – 37 mm in the crack path.

Fig. 8: SIF at 0% interference level.

At the initial crack size of 7 mm, the SIFs at both the crack tips are very close, with around 5 % difference. With the crack advance towards joint 2, difference in SIF between the tip 2 and tip 1 increases. As the crack starts approaching the joint L2, SIFs at both crack tips reach identical value and just before reaching the joint, SIF at crack tip 1 surpasses the SIF at crack tip 2. After passing the joint L2, the SIFs repeat the previous pattern with SIF at crack tip 2 greater than that at crack tip 1, till the joint L1 is reached. Then, near the joint L1, SIF at tip 1 surpasses the SIF at tip 2. After passing the joint (2a=37 mm), SIFs at crack tips 1 and 2 become identical due to symmetry of the crack. It was also observed that, when the crack is resumed after passing the joints, SIFs at tip 1 are a little less than the values obtained just before reaching the crack. At joint 2, it was 1.85% lower and at joint 1 it was 3.34%. It was observed that, as the interference increases, the difference of SIFs at crack tips 1 and 2 reduces except when the crack is nearest to the joint location, where SIF at crack tip 1 dominates the value at tip 2. It can be seen in the Fig. 9-10, plotted for interference levels of 0.15% and 0.3%.