PSI - Issue 68

Bahman Paygozar et al. / Procedia Structural Integrity 68 (2025) 1166–1172 Bahman Paygozar et al. / Structural Integrity Procedia 00 (2025) 000–000

1168

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bending (SENB) specimens used in Mode I and II tests and the TSCP specimen used in Mode III test are mentioned in the relevant references (Linul et al. 2020, Guillén-Rujano et al. 2021). Fig.1 indicates three specimens under different fracture tests. The obtained material properties of the PLA are listed in Table 2.

(a) (c) Fig.1. Illustration of different tests utilized to extract the fracture properties of the PLA material: (a) Mode I symmetric four-point bending, (b) Mode II asymmetric four-point bending, and (c) Mode III transverse shear cracked plate tests. (b)

Fracture Toughness [ √ ] Mode II Mode III

Table 2. The mechanical properties of PLA material. Yield Strength [MPa] Young’s Modulus [MPa] Mode I

Fracture Energy [N/mm]

Mode I

Mode II

Mode III

34

3188

3.73

3.79

3.23

3.89

4.02

4.35

2.2. Micro-CT imagining In the 3D-printing lattice by the FFF technique, when the layers appearing in the sliced model in Fig. 2(a) are fabricated, they create geometric unevenness on the surface, and gaps may occur between the print lines inside. The process parameters used in fabricating the lattices are listed in Table 1 (Paygozar and Gorguluarslan 2023a). A detailed 3D model was obtained to characterize these uncertainties by combining the scanned images extracted with the micro computed tomography (CT) as a non-destructive testing method before any damage is done. The micro-CT imaging was conducted by a Skyscan 1272 Micro-CT device (Bruker company) in HUNITEK with details in 10 microns. The lattices’ solid models were created in ABAQUS and then sliced in Cura software before printing (see Fig. 2(a)). Taking account of the capacity of the micro-CT machine's container, it was decided that each five-sample lattice would be put together to speed up the process. One 3D-printed specimen, including five identical BCC lattices fabricated with a 1.5 mm strut diameter and a configuration of 5×5×5, is shown in Fig. 2(a). Some selected micro-CT images taken from the lattices, representing all the defects inside lattices, are shown in Fig. 2(b). 2 mm 1 mm

Sliced sample