Mechanical performance and energy absorption of Ti6Al4V functionally graded diamond TPMS lattice bionic metamaterials manufactured via selective laser melting

The improvement of compressive and energy absorption properties of titanium alloy lattice-structured metamaterials is essential for critical applications such as engine structural components in the aerospace field. In this paper, inspired by walnut shells, a Diamond-X (DX) lattice-structured metamaterial fusing Diamond surfaces with X-shaped plates was designed, and the design of linear and symmetric gradient structures with different relative density orientations was presented. Predictions of high-stress areas and damage forms were performed by finite element simulation, and samples of Ti6Al4V material were printed for quasi-static compression testing. The results showed that, compared to the Diamond structure with the same density (2.70 g/cm 3 ), the DX structure exhibited a 36.32% increase in yield strength, a 40.38% increase in compressive strength, and a 129.83% increase in energy absorption capacity. The symmetric gradient design of the reverse relative density improved energy absorption by 161.60%. Overall, this study presents a new bionic design concept and gradient combination approach that extends the design space of functional gradient lattice structures.