Effect of unit cell topology on the tensile loading responses of additive manufactured CoCrMo triply periodic minimal surface sheet lattices

This study involves the fabrication of triply periodic minimal surface sheet lattices possessing two different topologies—Neovius and Schoen’s IWP. The structural characteristics of these materials, which were fabricated by laser powder bed fusion using CoCrMo alloy powder, were investigated. The tensile properties and deformation behavior of the materials were evaluated by increasing the unit cell size (1, 2.5, and 5 mm) for each topology. The results of the tensile tests showed that the yield strengths and Young’s moduli of both topologies decreased, and that their elongations increased with decreasing unit cell size. We compared the mechanical properties of the Neovius and IWP lattices, which had the same unit cell size, and found that the former exhibited higher yield strength, tensile strength, and elongation. Further, the tensile deformation behavior of the specimens was analyzed by applying the Gibson–Ashby analytic model. The Neovius lattice accommodated more uniform deformations in a greater number of cell layers. These experimental observations and the use of a simplified model of the lattice structure can enhance the understanding of the mechanism of the room-temperature tensile deformation of Neovius and IWP sheet-based lattice structures.