PSI - Issue 71

Poshadri Chathri et al. / Procedia Structural Integrity 71 (2025) 309–316

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ratio of 0.69 for all conditions. The percentage reduction in peak force for random (spherical and different) shaped pits with inline and random orientations is 2.38%, 2.45%, 3.65%, and 2.01%, while the reduction in displacement is 12.60%, 12.92%, 18.31%, and 10.94%, respectively, when compared to without pits. In the case of specimens with an aspect ratio of 1.56 in all testing conditions, also observed reduction in both force and displacement values. Here, the percentage reduction in force for random (spherical and different) pit shapes with both inline and random orientations is 3.67%, 4.26%, 3.55%, and 3.41%, while the decrease in displacement is 17.71%, 20.02%, 18.92%, and 15.14%, respectively. And also, there is a reduction in force and displacement values observed in specimens having an aspect ratio of 1.76 in all conditions. The overall percentage reduction in force for random (spherical and different) pit forms with both inline and random orientations is 0.69%, 1.15%, 1.17%, and 0.68%, while the reduction in displacement is 2.64%, 3.78%, 8.64%, and 5.09%, respectively.The force-displacement comparison for pits of different shapes and aspect ratios in both inline and random orientations. Spherical pits tend to have better strength and elongation compared to other shapes. For an aspect ratio of 1.76, non-spherical pits in inline orientation show a slight 1.167% decrease in strength and an 8.639% improvement in toughness compared to the original specimen. However, at an aspect ratio of 1.56, spherical pits in inline orientation have a larger strength drop of 3.665%, while non-spherical pits see a significant 18.910% decrease in elongation. For random orientation at an aspect ratio of 1.76, pits of different shapes have a minor strength reduction of 0.682%, while spherical pits improve elongation by 3.779% compared to the original specimen. At an aspect ratio of 1.56, however, spherical pits experience a 4.259% reduction in strength and a substantial 20.019% drop in toughness.

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Fig .7. Force vs Displacement distributions comparison of all aspect ratios of pits a. inline orientations b. random orientations In the overall comparison shown in Fig. 8a-b, for all aspect ratios of pits with both orientations, the maximum force is generated for pits with a random orientation and an aspect ratio of 1.76, while the minimum force is observed for spherical pits with a random orientation and an aspect ratio of 1.56. It was observed that as the aspect ratio increased, it means the depth of the pit got increased. This will result a spike in stress concentration factor (SCF) this leads to a reduction in specimen strength. Due to this, strength initially decreased where the depth of the pit is less, and then increased due to the rise in the depth of the pit. Regarding displacement, spherical pits with a random orientation and a 1.76 aspect ratio (depth of pit is high) exhibited the highest displacement, whereas spherical pits with a random orientation and a 1.56 aspect ratio (depth of pit is low) showed the lowest displacement. In comparing all aspect ratios, the 1.76 ratio demonstrates greater strength and toughness, while the 1.56 ratio exhibits poor strength and toughness because the depth of the pit. This is attributed to the aspect ratio parameter, where pits with greater depth tend to have reduced strength and elongation.

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Figure 8. a . Comparison of force vs. specimen conditions, b. Displacement vs specimen conditions