Energy absorption behavior of stiffness optimized graded lattice structures fabricated by material extrusion

The objective of this study is to investigate the energy absorption performance of the graded lattice energy absorbers designed by a stiffness-based size optimization process under static loadings applied during the in-service conditions. The energy absorber geometry is modeled using three different lattice types, namely complex cubic, octet cubic, face- and body-centered cubic. The stiffness-based size optimization subjected to a static bending load is conducted to determine the optimal strut diameters which produced graded lattice structure designs. To investigate the energy absorption behavior of these graded lattice designs, the nonlinear dynamic explicit finite element analysis (FEA) is conducted under quasi-static compression for each design. The lattice designs are fabricated by a material extrusion technique using the polylactic acid material and the quasi-static uniaxial compression tests are conducted on the fabricated designs. The FEA results are found to be in good agreement with the experimental results. When compared with uniform counterparts, the presented graded lattices exhibit the improved energy absorption in response to uniaxial compression although their designs were derived from a stiffness-based size optimization with bending load.