Energy absorption characteristics and failure deformation of novel blend lattice structure for weight reduction applications

Lattice structures are increasingly employed in aerospace and biomedical applications due to their exceptional strength-to-weight ratios, enabling lightweight designs. These structures include strut and surface-based configurations, which are effectively manufactured through additive manufacturing (AM) techniques. Among these, the integration of multiple lattice designs has been explored to enhance mechanical properties such as stiffness and strength. This study examines the deformation behaviour and compression properties of the octet, gyroid, and blend (merging of octet and gyroid) lattice structures. All the structures were fabricated with poly-lactic acid (PLA) using a material extrusion AM process at a relative density of 64%. Quasi-static compression tests reveal distinct deformation mechanisms across the lattices. The octet lattice exhibited stretching-dominated behaviour, with an increase in the elastic modulus and a 12.3% improvement in stiffness compared to the gyroid. Conversely, the gyroid lattice demonstrated bending-dominated behaviour, resulting in greater energy absorption due to a smooth, longer plateau region and a higher peak stress observed. During quasi-static compression, the blend lattice exhibits post-yield softening, resulting in a decrease in stress after the yield point due to a change in deformation mechanism from stretching to bending-dominated. The energy absorption capacity was measured as 3.53 J/cm 3 for the blend lattice, which was intermediate between the octet (0.73 J/cm 3 ) and gyroid (5.19 J/cm 3 ) structures. This balance of properties makes the blend lattice suitable for applications that require moderate energy absorption and improved stiffness. To further explore their application, a combination of octet and gyroid lattice designs was integrated into the topology optimisation of a bracket using a density-based approach.