Ultrafast Shape‐Reconfigurable Chiral Mechanical Metamaterial based on Prestressed Bistable Shells

Abstract Fast shape‐reconfiguration with large morphing amplitude is crucial for intelligent materials/structures that require tunable functions and adaptivity to different environments. However, the morphing strategies are rare in combining ultrafast speed, large amplitude, and high energy‐efficiency simultaneously. Herein, a class of 2D and 3D chiral mechanical metamaterials are proposed to tackle this challenge based on prestressed bistable metallic shells. The metamaterial is architected by cylindrical cores and slender bistable shells with an anti‐chiral arrangement. The bistable shell has a flat extended shape and a rolled‐up shape that can wrap on the connected cylindrical cores compatibly, and thus endow the metamaterials with a tunable morphing amplitude that can even extend to infinity. By experiments, simulations and theoretical modelling, it is demonstrated that the bistable shell can transform from the extended state to the rolled‐up state with a transitional speed of 7.56 m s⁻¹, which provides the 2D and 3D metamaterials with 25.38‐ and 101.14‐times body area/volume variation per second, respectively. Moreover, a smart trapper for capturing moving objects and a phononic structure with tunable band gaps are realized based on the metamaterials. This work provides a straightforward platform to design metamaterials and their derived systems with ultrafast and large‐amplitude shape‐reconfigurability.