Development of strong, stiff and lightweight compression-resistant mechanical metamaterials by refilling tetrahedral wireframes

Porous materials with excellent load-bearing capacity are essential for aerospace, shipbuilding, and biomedical devices where lightweight structures are required. In this study, a design strategy of mechanical metamaterials with a shell-based structure is proposed. By re-filling curved surfaces in the tetrahedral wireframe, closed cavities inside the structure are eliminated and the manufacturability is improved. The modified tetrahedron is mirrored, cut with specific proportions (25%, 50%, and 75%), and arrayed to form different structures. The compression performance of the structure is investigated using stereolithographic specimens and numerical methods. Compared with the mechanical metamaterials based on triply periodic minimal surfaces (TPMS) and strut-based structures, the new shell-based structures exhibit excellent strength and stiffness. The compressive strength and Young's modulus of the structure with 50% cutting proportion are increased by 65% and 80%, respectively, compared with the Gyroid structure. This study offers a new design strategy for mechanical metamaterials with excellent compression-resistant capability.