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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Figure 3. Tensile setup (A), extensometers attached to the tested specimen, and thermal camera (B). Thermal camera monitoring (C). The thermal conductivity and thermal effusivity of PLA samples with varying infill geometries were measured using a C-Therm Trident thermal analyzer equipped with a Modified Transient Plane Source (MTPS) sensor. This technique employs a transient method, allowing for rapid, non-destructive analysis with minimal sample preparation. PLA samples were 3D printed in a disc shape with a diameter of 18 mm and a thickness of 8 mm. 3. Results and Discussion 3.1. Tensile result 3.1.1 Load-displacement and Stress-strain The mechanical behavior of five distinct infill structures was investigated under uniaxial tensile loading using a universal testing machine. The displacement was applied through a hydraulically driven crosshead, and the tensile strength was determined based on the applied load at the fracture point. The stress–strain and load–displacement responses of the specimens are illustrated in Figures 4a and 4b, respectively.

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Figure 4. Stress-strain (a) and Load-displacement (b) curves for different infill patterns.

Among the tested structures, the Octet lattice showed the highest peak load (1.38 kN at 0.56 mm), indicating superior stiffness due to its stretch-dominated topology. However, the sharp post-peak drop indicates brittle failure, likely from localized instability. The Cubic (1.25 kN) and Quarter-Cubic (1.22 kN) lattices followed similar trends, both failing abruptly after their peaks near 0.5 mm. In contrast, the Lines structure exhibited a lower peak load (1.1 kN) but sustained it over a broader displacement range (1.8 mm), suggesting better energy absorption and deformation tolerance typical of bending-dominated systems. The Triangles structure behaved similarly, peaking at 1.18 kN and transitioning to a more ductile failure mode. Engineering stress–strain curves support these trends: the Octet reached the highest stress (30 MPa), followed by Cubic (28.5 MPa) and Quarter-Cubic (28 MPa), all showing immediate post