PSI - Issue 77

Pawel Madejski et al. / Procedia Structural Integrity 77 (2026) 323–330 Author name / Structural Integrity Procedia 00 (2026) 000–000

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peak softening. Lines (26 MPa) and Triangles (25 MPa) had lower peak stresses but maintained strain over longer intervals, indicating improved ductility and strain redistribution.

3.1.2. Ultimate tensile strength, Elastic modulus, and Poisson’s ratio

Among the geometries, the Octet lattice showed the highest ultimate tensile strength (UTS) at 30.43 MPa, due to its well-connected nodal network (Figure 5). The Cubic and Quarter-Cubic structures followed with UTS values of 27.33 MPa and 26.97 MPa, while the Triangles structure had the lowest (24.08 MPa), making it more suitable for lightweight, low-load applications like tissue scaffolds. In stiffness, measured by elastic modulus, Triangles ranked highest (2.349 GPa), closely followed by Octet (2.253 GPa). The Lines structure had the lowest stiffness (2.017 GPa), favoring flexibility for compliant designs. Octet’s combination of high strength and stiffness supports its suitability for bone-mimetic applications. Poisson’s ratio revealed further distinctions: Lines had the highest (0.453), indicating greater lateral expansion and suitability for soft tissue mimicry, while Quarter-Cubic had the lowest (0.256), suggesting better dimensional stability. Octet and Triangles showed intermediate values (0.342), balancing ductility and stability.

Figure 5. Ultimate tensile strength, Elastic modulus, and Poisson’s ratio for different infill patterns . 3.1.3. Thermo-mechanical analyses Thermal imaging during the tensile test for the Cubic pattern group, as a representative sample, reveals a gradual temperature rise in the region of impending damage, peaking just before fracture (Figures 6 and 7). This localized heating is due to internal friction and microstructural rearrangements as the sample undergoes strain, a phenomenon known as the thermoelastic effect. The observed temperature plateau just before failure (visible on the time– temperature chart) aligns with the onset of maximum stress, after which both stress and temperature decrease sharply following material rupture.