PSI - Issue 77

Pawel Madejski et al. / Procedia Structural Integrity 77 (2026) 357–364 Author name / Structural Integrity Procedia 00 (2026) 000–000

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F igure 12. A) Segmented image of Triangles pattern (slice 8) using Watershed method; and B) Overlay pore detection, green colour denotes pores.

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F igure 13. A) Segmented image of Triangles pattern (slice 8) using Region-growing method; and B) Overlay pore detection, green denotes pores.

Figure 14. A) Percentage porosity across 15 sliced images; and B) Porosity distribution of Triangle pattern.

For the Triangle pattern, the total porosity values were generally higher than those for Lines, ranging from approximately 9% using the adaptive threshold and Otsu method to over 16% using the watershed method. However, defect porosity was markedly lower across methods, typically below 3%, indicating that the triangular infill geometry promotes fewer manufacturing defects relative to voids deliberately designed for infill. Region growing for triangles showed lower structural porosity, around 2.54%, suggesting a more conservative segmentation of the internal voids, which is compatible with the designed infill pattern. The higher structural porosity but lower defect porosity in Triangles pattern points to an infill design that favors intentional voids at the expense of defect formation, possibly due to better heat distribution and material deposition stability during printing. The density verification revealed a somewhat wider range of deviations between the estimated and experimental densities (1.188 g/cm³). The Otsu and adaptive thresholding methods yielded deviations within ±6.3%, showing reasonably consistent density estimation and successful discrimination of structural and defect porosity in this pattern. However, watershed segmentation resulted in the largest overestimation (+14.9%), reflecting similar challenges faced in the Lines pattern where it tends to over-segment pores and inflate the solid volume estimate. Region growing also showed a positive deviation (+7.1%), though less pronounced. The higher structural porosity and lower defect porosity characteristic of the Triangles pattern suggest that its designed voids are accurately captured by segmentation; however, the segmentation method's sensitivity affects the precision of density calculation.

Table 4. Structural, defect, and total porosity for Triangles pattern Segmentation Method Structural porosity [%] Defect porosity [%] Total Porosity [%] Otsu 8.85 0.61 9.46 Adaptive-threshold 8.74 0.31 9.05 Watershed 13.72 2.54 16.26 Region growing 2.54 0.63 10.19