Mechanical properties of additive manufactured variable-density Kelvin lattice structures: a novel design method for Kelvin unit cells

Behaviors associated with the mechanical responses of a Kelvin unit cell can be improved by optimizing the parameter sets. Herein, we present a shape control method for a Kelvin unit cell by functionalizing the coordinates of 24 vertices. Further, we verified the physical properties of Kelvin lattice structures using relative density and lattice patterning through finite element analysis (FEA). Consequently, we devised a design method for the Kelvin unit cell that can control the cell aspect ratio. Furthermore, we estimated the relative density using the strut section and interior angles of a hexagon as variables, and achieved an accuracy of 96.3–99.7%. The FEA results revealed that with an increase in the relative density of the 1 × 1 × 1 lattice structure of titanium alloy to 0.00800, 0.03065, 0.11194, 0.22789 and 0.36246, the yield strength sharply increased to 0.67, 2.79, 10.23, 27.27 and 51.82 MPa, respectively. When the 1 × 1 × 1, 2 × 2 × 2, 3 × 3 × 3 and 4 × 4 × 4 lattice structures were configured with H,W=202 mm, the yield strength of the lattice structure converged in the 3 × 3 × 3 pattern.