Isotropic energy absorption of topology optimized lattice structure

Lightweight lattice structures received much attention recently because of their high specific mechanical properties and usefulness in biomedical, heat dissipation, and energy absorption applications. However, most of the investigated lattice structures are anisotropic, which leads to variations in performance depending on the direction of deployment. For example, in many energy absorption applications, direction-independent energy absorption may be an advantage. This paper investigates the energy absorption of a 3D printed titanium-based isotropic topology optimized lattice structure under quasi-static compression. Simple cubic and body-centered-cubic lattices were also investigated for comparison. Finite element analysis (FEA) was used to evaluate the compressive behavior of the lattice structures, while laser powder bed fusion was used to manufacture selected lattice structures and validate the FEA model via experimental testing. The effects of lattice topology and relative density on the mechanical behavior were investigated both numerically and experimentally. Lattices were loaded at different orientations to evaluate the energy absorption isotropy. The results showed that the topology optimized lattice exhibits a mixed stretching and bending deformation mode. Moreover, the topology optimized structures showed higher or comparable relative energy absorption than triply periodic minimal surfaces. The topology optimized lattice also showed nearly perfect SEA isotropy, which may be beneficial in energy absorption applications.