Hierarchical mechanical metamaterials built with scalable tristable elements for ternary logic operation and amplitude modulation

Abstract

Multistable mechanical metamaterials are artificial materials whose microarchitectures offer more than two different stable configurations. Existing multistable mechanical metamaterials mainly rely on origami/kirigami-inspired designs, snap-through instability, and microstructured soft mechanisms, with mostly bistable fundamental unit cells. Scalable, tristable structural elements that can be built up to form mechanical metamaterials with an extremely large number of programmable stable configurations remains illusive. Here, we harness the elastic tensile/compressive asymmetry of kirigami microstructures to design a class of scalable X-shaped tristable structures. Using these structure as building block elements, hierarchical mechanical metamaterials with one-dimensional (1D) cylindrical geometries, 2D square lattices, and 3D cubic/octahedral lattices are designed and demonstrated, with capabilities of torsional multistability or independent controlled multidirectional multistability. The number of stable states increases exponentially with the cell number of mechanical metamaterials. The versatile multistability and structural diversity allow demonstrative applications in mechanical ternary logic operators and amplitude modulators with unusual functionalities.

A mechanical metamaterial with reprogrammable logical functions

“…Note that in prior works involving buckling beams 7 , 29 , 33 there is no way to input energy to the system along the signal transmission path, limiting the number of gates that can be cascaded until the propagating energy is not enough to trigger buckling. In our system, the signal elements along the signal path can receive energy input through successively applied excitations, which can help the information to be transmitted without attenuation over long distances.…”

Responsive materials architected in space and time

“…6b ). Similar concepts of mechanical logic gates have been implemented in additively manufactured architectures that incorporate multi-stable mechanisms at centimetre and micrometre scales, yielding a variety of functionally complete logic gates that output specific displacement based on mechanical 182 , 183 (Fig. 6c ) or chemical 184 inputs.…”

Research progress and development trend of smart metamaterials

“…Under the external stimulus, the shape, property or function of the object will change with time. Stimulus-responsive shape memory materials based on 4D printing have the advantages of simple manufacturing process, large SMMs have gradually become a new protagonist in the field of materials and have been endowed with richer functional properties, including reconfigurable [65, 66], programmable [67], elastic wave propagation control [68,69] and mechanical computing [70,71]. et al In the future, the functional properties of natural materials will gradually diminish.…”