Multistable mechanical metamaterials are artificial materials whose microarchitecture offers more than two different stable configurations. Existing mechanical metamaterials rely on origami or kirigami-based designs with snap-through instability and microstructured soft mechanisms. Scalable structures that can be built from mechanical metamaterials with an extremely large number of programmable stable configurations remain elusive. In a new report now published on Science Advances, Hang Zhang and a research team in engineering, electronics, and advanced structure technology in Beijing China, used the elastic tensile/compressive asymmetry of kirigami microstructures to design a class of X-shaped tristable structures. The team used these constructs as building block elements to build hierarchical mechanical metamaterials with one-dimensional cylindrical geometries, 2D square lattices and 3D cubic or octahedral lattices with multidirectional multistability. The number of stable states increased with the cell number of mechanical metamaterials incorporated in the work, and the versatile multistability and structural diversity demonstrated applications within mechanical ternary logic operators with unusual functionalities.
