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

388

11

4.3. Correlation between structural morphology and damage distribution Consistent with the high compression strength observed in Fig. 11, the cross-sectional area analysis in Fig. 10b reveals that Neovius and IWP structures possess a higher frequency of the largest cross-sectional areas. The Gyroid unit cell has the lowest prevalence of large cross-sections as shown in Fig. 10a, suggesting a concentration of potential weak spots in its structure. This observation coincides with its lower compression strength in Fig. 11. The minimal oscillation of the Primitive unit cell’s cross-sectional graph in Fig. 5 may contribute to its observed robust behavior, evidenced by the plateau shape of its stress-strain curve. Fig. 13 visualizes the correlation between cross-sectional area in the cutting direction, inclination angle, and damage propagation. The left-hand figure illustrates the final state of compressive damage by FE analysis. The red X marks on the middle graph indicate the regions with small cross-sectional areas and are considered potential damage areas. The distribution of inclination angle is presented in the right-hand figure. This analysis revealed a strong correlation between the potential damage regions based on cross-sectional area analysis and the crack propagation patterns predicted by the FE models. In Fig. 13d, it is evident that abrupt changes in the cross-sectional area of IWP structure amplify the stress concentration because the force distribution needs to readjust significantly within the width variation region (Muminovic et al. (2015)). Analysis of the inclination angle distribution shows that cracks tend to initiate in regions with very steep inclinations (see Fig. 12, 0.5% strain) and then propagate along regions inclined vertically at angles greater than 55 ° (see Fig. 13). Under uniaxial compression, maximum shear stress occurs at ±45 ° to the load (Marciniak et al. (2002)). Vertically inclined TPMS surfaces often align closely with these maximum internal stress directions, facilitating easier crack initiation and growth along them. Furthermore, a vertically inclined surface is not perpendicular to compressive loading. This resolves the load into shear and bending forces along the surface, reducing effective stiffness by not fully utilizing the material's strength. This misalignment causes stress concentration in the surrounding region. This observation is supported by Fig. 14, which shows that high von Mises Stress (indicated in red) on the left figure is more distributed in blue-shaded regions with steep inclination angles on the right figure. The von Mises stress was evaluated at , before the initiation of cracks.

Fig. 13 Damage propagation by FE modeling (left figure), Potential damage regions identified by small cross-sectional areas (middle graph) and color-encoded distribution of inclination angle (right figure) of a) Primitive; b) Gyroid; c) Neovius; d) IWP.