Influence of manufacturing process-induced geometrical defects on the energy absorption capacity of polymer lattice structures

Modern additive manufacturing processes enable fabricating architected cellular materials of complex shape, which can be used for different purposes. Among them, lattice structures are increasingly used in applications requiring a compromise among lightness and suited mechanical properties, like improved energy absorption capacity and specific stiffness-to-weight and strength-to-weight ratios. A dedicated modeling strategy to assess the energy absorption capacity of lattice structures under uni-axial compression loading is presented in this work. The numerical model is developed in a non-linear framework accounting for the strain rate effect on the mechanical responses of the lattice structure. Four geometries, i.e., cubic body centered cell, octet cell, rhombic-dodecahedron and truncated cuboctahedron 2+, are investigated. Specifically, the influence of the relative density of the representative volume element of each geometry, the strain-rate dependency of the bulk material and of the presence of the manufacturing process-induced geometrical imperfections on the energy absorption capacity of the lattice structure is investigated. The main outcome of this study points out the importance of correctly integrating geometrical imperfections into the modeling strategy when shock absorption applications are aimed for.