Dissipative dual-phase mechanical metamaterial composites via architectural design

Dual-phase mechanical metamaterials, fabricated as a hybrid of two architected lattice materials with different mechanical properties and bioinspired patterning, have been shown to exhibit improved combination of properties, such as enhanced reinforced strength and toughness. In this study, we specifically examine the selection of the reinforcement phase, specifically involving the effects of its structural architecture, in terms of connectivity and interfacial structure, on the resulting mechanical properties and deformation mechanisms of such dual-phase lattice composites. The composites are simply fabricated using selected laser melting based additive manufacturing. Using quasi-static compression tests and simulation studies, we find that enhancing the role of the reinforcement phase (RP), connection phase (CP) and their interfaces, by employing more trusses distributed along the loading direction, can dramatically improve mechanical properties and energy absorption. By such architectural design of the connection phase, the specific stiffness, specific strength, and specific energy absorption of the dual-phase lattice composites can be optimized, respectively by 77%, 7% and 51% compared to the unreinforced matrix phase lattices. This suggests that the design space of mechanical metamaterials can be significantly expanded by architectural and phase selection together with bioinspired phase patterning.