Laser printed bio-inspired active flexible metallic metamaterials with reconfigurable deformation capability

Metamaterials are excellent candidates for application in smart morphing aircraft owing to their high designability, excellent mechanical and functional properties. However, existing designs often utilize passive structures and polymer-based materials, limiting the lightweight and strength of the morphing wings. Hence, we proposed a novel active flexible metal metamaterial inspired by the embedded characteristics and wavy interfaces of epidermal cells in the Portulaca oleracea seedcoat, with network honeycomb configuration. The formability, mechanical properties, deformation mechanisms, and the shape memory effect (SME) of network honeycombs manufactured by laser powder bed fusion (LPBF) were systematically investigated. By regulating the number of cell walls per junction, network honeycombs achieved tunable mechanical properties with the Poisson’s ratio ranging from -0.21 to +0.47. The hexagonal network honeycombs (HNHs) demonstrated a fracture strain up to 38% and achieved an excellent shape recovery ratio of 96.10% under thermal activation with 10% pre-programmed strain. The reconfigurable deformation capability of the biomimetic metamaterial was demonstrated in morphing wings within a wide application temperature range, enabling smooth and continuous deformation within a range of -25° to 25°. This study highlights the integration of shape memory alloy to endow metamaterials with active and reconfigurable properties, advancing the engineering applications of smart morphing aircrafts.