In-plane compression behavior of hybrid honeycomb metastructures: Theoretical and experimental studies

Auxetic cellular structures with outstanding mechanical performance and unique deformation characteristics have a variety of potential applications in aerospace, as ultralight load-bearing structures and vibration isolation structures. Herein, the in-plane compression behaviors of hybrid honeycomb metastructures, comprised of conventional and auxetic honeycombs, are systematically studied by using theoretical calculations, experimental characterization and numerical simulations. The theoretical formulae of elastic modulus and ultimate strength of the architected metastructure are derived by establishing stress analysis models. Three types of hybrid honeycomb metastructures are manufactured by selective laser melting (SLM) with 304 stainless steel. Finite element analysis is performed to unveil the deformation mechanism and failure modes. The theoretical prediction results of elastic modulus and ultimate strength are consistent with simulations and experimental results. In addition, the influences of panel and layer numbers on the mechanical behavior of hybrid honeycomb metastructures are discussed in detail. The results reveal that a hybrid metallic honeycomb metastructure, with stable and superior compressive properties, can be obtained by combining two types of cellular cells, i.e., conventional and auxetic honeycombs. These results provide a baseline for further research and development of novel metastructure designs.