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

1169

4

3 mm

4 mm

3D-printed sample

(a) (b) Fig. 2. Illustration of a specimen of five identical BCC single-cell lattices: (a) sliced in Cura software and 3D-printed and (b) selected micro-CT images corresponding to four different heights as written onto each image.

2.3. Tensile experiments For validation purposes, after conducting micro-CT tests, the lattices were separated from the PLA base and attached to the steel bars using a two-component structural adhesive, Araldite 2015, to fabricate single-cell lattice specimens. Fig. 3 shows an adhesive joint under tensile testing in a universal testing machine (Instron 5944, USA) with a 1mm/min loading speed. The load-displacement response was extracted to be used for comparison purposes.

Upper steel adherend

Lattice cell

Lower steel adherend

Fig. 3. Demonstration of an adhesively bonded single-cell BCC lattice specimen under tensile loading.

3. Numerical study 3.1. Theory and formulation

The XFEM technique and the formulation involved therein were previously published by the authors in detail (Paygozar and Gorguluarslan 2024). The XFEM permits the crack to propagate through the element interior due to its enrichment functions added to the conventional FEM. This method can model the crack initiation and propagation process by a cohesive traction-separation law defined in a cohesive zone model (CZM) (Paygozar and Gorguluarslan 2023b, Sadigh et al. 2018). To use the traction-separation law in ABAQUS, the MaxPS criterion was selected in this study to model the crack initiation (Campilho et al. 2011). According to this criterion (Eq.1), when the maximum principal stress $ # & in an element reaches the ultimate strength ( $ ) of the material, the failure in that element starts. The failure equation is given by