PSI - Issue 71

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

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In the case of 0.15% interference, 14% more SIF was found for 7 mm and 8 mm crack lengths at hole 5, as plotted in Fig. 8. So Fig. 5-8 shows that the % difference in SIF was consistently higher for Hole-5 compared to Hole-4 for all three interference levels. 3.3. Deviation of MERR-based crack path from plane perpendicular assumption Crack propagation based on the Maximum Energy Release Rate (MERR) criteria resulted in a significant deviation from the crack path assumed to be in the plane's perpendicular direction. Figs. 9 and 10 illustrate the crack path deviation from the assumed plane-perpendicular direction at locations H1 and H2, respectively. The spatial coordinates of the MERR-based crack path were precisely traced and plotted on an X-Y graph, with the centers of the corresponding holes set as the origin to quantify the angle deviation as discussed in the section 2.4. The deviation of the crack path initiating from hole 1 with no interference is found to be 39.4 ° , which is identical for both the crack tips due to symmetry. At hole 2, crack tip 2 exhibits a maximum 15.65 ° crack path deviation. The deviation angles for all other hole locations and interference levels are detailed in Table 2. For Crack tip-1, angle deviation from the assumed crack path is more significant for Hole-5 than Hole-4, up to 0.1% interference. However, at 0.15% interference, deviation becomes more pronounced for Crack tip-1 at Hole-4, reaching 12.2 ° . Conversely, Crack tip 2, shows a larger deviation of 13.6 ° at Hole-4.

Fig. 9. Deviation of MERR based crack path (Based on ABAQUS results) from the Plane perpendicular crack path (represented as red solid line) at Hole-1

Fig. 10. Deviation of MERR based crack path (Based on ABAQUS results) from the Plane perpendicular crack path (represented as red solid line) at Hole-2

Table 2. Deviation of crack path from plane perpendicular crack path for different location with different interference levels. Interference Level Location of Crack

The Angle of Deviation of Crack Path From The Y-Axis (Plane Perpendicular Crack Path) Crack tip 1 Crack tip 2

39.4 ° 7.5 ° 1.4 ° 3.6 ° 9.7 ° 11.3 ° 12.2 ° 11.5 °

39.4 ° 15.7 ° 4.5 ° 3.5 ° 11.2 ° 11.3 ° 13.6 ° 11.5 °

0%

H1 H2 H4 H5 H4 H5 H4 H5

0.1%

0.15%

3.4. Effect of interference on the crack path The influence of interference on the crack path was further analyzed for Holes 4 and 5, as these are located in the most critical row, with two most beneficial interference levels: 0.1% and 0.15%. With increasing interference levels, a significant deviation in the crack path from the plane perpendicular assumption, as reported in the literature[Hithendra and Prakash, (2021)] was observed at Hole 4, as depicted in Fig. 11(a) for both the crack tips based on the ABAQUS ® simulation across various level of interference. Similarly, at Hole 5, the crack path deviation increased with higher interference levels. Fig. 11(b) indicates that the deviation angles are identical for both crack tips at each interference level, attributable to symmetry. Additionally, it was noted that for cracks at Hole 5, the crack path deviations are nearly equivalent at 0.1% and 0.15% interference level.