Experimental and numerical characterization of imperfect additively manufactured lattices based on triply periodic minimal surfaces

• Published in: Materials & design Vol. 233; p. 112197
• Main Authors: Günther, Fabian, Pilz, Stefan, Hirsch, Franz, Wagner, Markus, Kästner, Markus, Gebert, Annett, Zimmermann, Martina
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-09-2023; Elsevier
• Subjects: Additive manufacturing; Imperfect lattices; Lattice structures; Numerical reconstruction; Triply periodic minimal surfaces; Triply periodic minimal surfaces; Imperfect lattices; Numerical reconstruction; Lattice structures; Additive manufacturing
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2023.112197

•Additively manufactured lattices based on triply periodic minimal surfaces exhibit excess material and surface roughness.•The presented modeling procedure enables the artificial reconstruction of the as-built morphology.•Using the reconstructed morphology drastically improves the accuracy of finite element simulations.•In the simulations, compressive stiffness and strength increase degressively with cell size.•The reconstruction procedure provides information about the mechanical degradation proportions of different defect types.
Lattices based on triply periodic minimal surfaces (TPMS) are attracting increasing interest in seminal industries such as bone tissue engineering due to their excellent structure-property relationships. However, the potential can only be exploited if their structural integrity is ensured. This requires a fundamental understanding of the impact of imperfections that arise during additive manufacturing. Therefore, in the present study, the structure-property relationships of eight TPMS lattices, including their imperfections, are investigated experimentally and numerically. In particular, the focus is on biomimetic network TPMS lattices of the type Schoen I-WP and Gyroid, which are fabricated by laser powder bed fusion from the biocompatible alloy Ti-42Nb. The experimental studies include computed tomography measurements and compression tests. The results highlight the importance of process-related imperfections on the mechanical performance of TPMS lattices. In the numerical work, firstly the as-built morphology is artificially reconstructed before finite element analyses are performed. Here, the reconstruction procedure previously developed by the same authors is used and validated on a larger experimental matrix before more advanced calculations are conducted. Specifically, the reconstruction reduces the numerical overestimation of stiffness from up to 341% to a maximum of 26% and that of yield strength from 66% to 12%. Given a high simulation accuracy and flexibility, the presented procedure can become a key factor in the future design process of TPMS lattices.