Mechanical Properties of Three-Dimensional Printed Combination-Design Truss Lattice Materials: Static and Dynamic Loading

Abstract

In this paper, four types of truss lattices are designed by combining octet truss (FCC) unit cells with other elementary unit cells, including Simple Cubic (SC), Body-centered Cubic (BCC), Body-centered Block (BCB), and Z-pinned (Z). The elastic properties (uniaxial, shear, and bulk moduli, Zener’s anisotropy index, and Poisson’s ratio), yield strength, deformation modes, and energy absorption under quasi-static loading, and impact resistance under dynamic loading of these lattices were investigated through finite elements. The initial peak stress and subsequent plateau stress are elevated under dynamic loading. The stress waves velocity of the lattices is calculated by the dynamic enhancement term. Results indicate that the mechanical properties of the designed lattices are better than the reported FCC and BCC lattices. FCCBCB (which is combined with FCC and BCB elementary unit cell) remains stable for uniaxial compression at a relative density of about 0.2 and exhibits the highest energy absorption capacity at the relative density considered; the Zener index of FCCSC (which is combined with FCC and SC elementary unit cell) does not vary greatly with the increase of relative density (1.18 to 1.11 at the relative density considered), and the Zener index approaches unity indicating elastic isotropy; and FCCZ (which is combined with FCC and Z elementary unit cell) features the highest yield strength and Young’ modulus among all lattices considered. The computational results are confirmed through uniaxial compression experiments on three-dimensional (3D)-printed specimens.