PSI - Issue 80

Thi Ngoc Diep Tran et al. / Procedia Structural Integrity 80 (2026) 378–391 Thi Ngoc Diep Tran/ Structural Integrity Procedia 00 (2019) 000–000

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Fig. 9 Cross-sectional area of IWP unit cell with corresponding cross-sectional shapes of high and low values on the graph.

Fig. 10 a) Overview of the cross-sectional area; b) Frequency distribution of cross-sectional area in four TPMS unit cells.

4.2. Compressive failure by FE analysis Fig. 11 compares four stress-strain curves, allowing a focused investigation of each geometry. The analysis reveals a hierarchy in compressive strength, where the IWP required the highest compression stress for the same amount of strain, followed by Neovius, Gyroid, and Primitive, respectively. The point at which cracks begin to form in each structure was indicated on the graphs by an X mark. This crack initiation appeared earliest in Primitive, followed by Gyroid, Neovius and IWP. The curve of Primitive exhibited a plateau shape instead of a sudden stress drop, which signified its ability to sustain a longer pressure. In the linear elastic region, minor stress fluctuations were observed under applied load, caused by localized cracks initiated at the interfaces between the TPMS unit cell and the rigid plate. These localized failures did not lead to a total collapse, allowing stress to accumulate until the abrupt drop. The corresponding damage development at 0.5%, 0.7%, and 1% of compression strain in four TPMS unit cells is illustrated in Fig. 12. Consistent with the observations in Fig. 11, cracks initiated and concentrated in the contact region with the rigid plates. At 0.7% of strain, Gyroid and IWP had not yet reached the maximum compression stress, contributing to a slowdown of crack propagation compared to Primitive and Neovius. Upon reaching 1% of strain, global cracks propagated differently in each structure, resulting in brittle fractures that lost all load-carrying capacity.