PSI - Issue 71

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

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3.3. Comparison of stress concentration factor (SCF) across all aspect ratios and orientations of pits Figure. 9a-b presents the distribution of the SCF for both inline and random orientations of spherical and various pit shapes. It was observed that pits with different shapes exhibit higher SCF values compared to spherical pits of the same shapes for all aspect ratios. Among the orientations, different-shaped pits with inline orientation show the highest SCF, indicating that they are more prone to initiating fractures earlier, as seen in Figure 9.c. For the random orientation, pits with a 1.76 aspect ratio demonstrate the highest SCF of 3.51, while spherical pits with an inline orientation and a 0.69 aspect ratio exhibit the lowest SCF of 2.87. Overall, as the aspect ratio increases, there is a corresponding increase in SCF across all pit shapes and orientations these are based purely on numerical simulation which does not consider any material defects. Also, this is totally based on mechanics consideration and needs validation with experiments.

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Figure 9. a . Comparison of SCF Vs. distance from hole to width a. inline orientation b. random orientation, c. SCF Vs Specimen ConditionsThe units are clear but font is very small. It needs to be increased for better visibility. 4. Conclusions This study provides an analysis of the mechanical properties and SCF of specimens containing both uniform and varied pit shapes, randomly distributed in both inline and random orientations with different aspect ratios. The following conclusions are drawn from the analysis. ● Multiple simulations revealed a reduction in the strength and elongation of specimens with pits compared to those without. The yield strength decreased by 3.8%, the ultimate strength decreased by 14.68%, and the percentage strain dropped by 4.96%. Failure occurs across various pit locations under all conditions, with inline pits exhibiting greater criticality than randomly oriented pits due to more significant reductions in strength and displacement. ● The comparison of force versus displacement for all aspect ratios with inline orientations reveals that spherical pits generally exhibit superior strength and elongation compared to other pit shapes. At an aspect ratio of 1.76, different shapes of pits show a strength reduction of 0.682%, and spherical random pits improve elongation by 3.78% relative to the original specimen. In contrast, at an aspect ratio of 1.56, spherical pits experience a 4.26% reduction in strength and a 20.02% decrease in elongation due to the aspect ratio parameter; pits with greater depth at an aspect ratio of 1.56 exhibited reduced strength and elongation. ● It was observed that as the aspect ratio increased, strength initially decreased and then increased. This is attributed to the aspect ratio parameter, where pits with greater depth have reduced strength and elongation.