Hierarchical bioinspired architected materials and structures

Designing new materials that are both lightweight, damage-tolerant, and sustainable is a primary requirement for the advancement of many technological fields. To date, lattice materials appear to be ideal candidates for achieving such multifunctionality at the material scale and leveraging the structural hierarchy can pave the way to amplify their performance. Nature teaches us that, by designing multiscale architectures through a "bottom-up"logic, it is possible to improve and fine-tune the properties of biological building blocks to get robust and multifunctional materials. Yet, we are still far from achieving such a level of perfection that Nature has. In an attempt to narrow this gap and understand the role of hierarchical strategies in lattice structures, we studied, by finite element modeling, 3D hierarchical lattice structures formed by "beam-based"elementary units. Specifically, we selected two types of unit cells with different mechanical behaviors, we combined them into different topological configurations - through hierarchy and engineering approach - and we studied their mechanical behavior under four-point bending loading. The results of this study are twofold: introducing structural heterogeneity by mixing different unit cell types can be beneficial in terms of mechanical properties, while introducing structural hierarchy does not lead to significant improvements in the deformation behavior of the lattice structures analyzed. The latter, however, significantly changes the surface-to-volume ratios of the lattice structures and thus extends their functionality. The evidence found may open new horizons for applications such as heat exchangers, mechanical filters, tissue regeneration scaffolds, energy storage systems, and packaging.(c) 2022 Elsevier Ltd. All rights reserved.