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

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Fracture energy Power-law criteria in 2D and 3D versions can be used to model crack propagation through damage evolution (Paygozar et al. 2020a, Paygozar et al. 2020b). ) % %& + + ) ' '& + + - ( ( & .=1 (2) Here, % , ' , and ( are strain energy release rates (i.e., fracture energies) in normal, first, and second shear directions with respect to the interface, respectively. Superscript C added to the previous parameters reflects their critical values: PLA material properties. 3.2. Voxel model generation and simulation In this study, the solid BCC lattice models (Fig. 5(a)), along with the voxel BCC lattice models, were investigated experimentally and numerically. The micro-CT images from each sample were regenerated through MATLAB programming to create 3D single-cell BCC voxel models (see Fig. 5(b)). They were created with a resolution of one voxel/four pixels. Defects like micro-cracks are also visible in the model. Later, the voxel models were imported into the ABAQUS environment to be analyzed using the XFEM technique under tensile loading. Several three dimensional, reduced integration, 8-node linear brick elements (C3D8R) with a size of 0.06 mm were utilized during simulations. However, various 10-node, quadratic tetrahedron elements (C3D10) of larger size (i.e., 0.23 mm) were utilized for the solid lattice models to economize on the computational costs, facilitating numerical analyses. In all the models, the whole lattice body was defined as the XFEM crack domain without inserting any pre-crack in the model; this allows the model to initiate the crack in any critical location of the model considering all the defects and geometrical conditions. As the boundary conditions, one side of each lattice was fully fixed (ENCASTRE), whereas the other side was introduced to move only in one direction ( ) = * = ) = * = + =0). 4. Results and discussion 4.1. Experimental and voxel-based numerical results Comparing the failure experienced in the tensile tests of adhesively bonded single-cell BCC lattice (Fig. 4(a)-Sec. A) and those obtained in voxel-based numerical analyses conducted via the XFEM technique (Fig. 4(b)-Sec. B). As shown in Fig.4, it can be understood that the numerical results are of high accuracy. In other words, the numerical investigation can predict the crack initiation and prediction path well.

Sec. A

Sec. B

(a) (b) Fig. 4. Comparison of the crack propagation experienced in a single-cell BCC lattice's (a) experimental test and (b) its corresponding numerical analysis (i.e., voxel-based approach).