Mechanical Response and Energy Absorption of 316L Stainless Steel Body-Centered-Cubic Functionally Graded Lattice Structures under Quasistatic Compressive Test

Five different density gradient variation strategies are proposed for body-centered-cubic (BCC) lattice structures in parallel to the loading direction prepared by selective laser melting with 316 L stainless steel as the building material, and the mechanical properties, deformation behavior, and energy absorption capacity of lattice structures with different density gradient variations and uniform lattice structure under compressive loading are investigated and compared. The results show that the elastic modulus and compressive strength of the uniform lattice structure are better than those of the lattice structure with density gradient parallel to the loading direction, provided that the relative densities are similar. However, through a reasonable design of density gradient, the lattice structure with density gradient parallel to the loading direction can obtain higher plateau stress than the uniform lattice structure and increase the onset densification strain to a certain extent, which obviously improves the energy absorption capacity of the lattice structure. The results obtained by finite-element calculations are in good agreement with the experimental results and can better restore the deformation behavior of the lattice structure under compressive loading. This work provides inspiration for the design of the density gradient of the lattice structure.