A programmable modular metamaterial with alterable Poisson’s ratio and multi-stability*

Modular metamaterials are artificially designed materials constructed by linked modules, often with properties surpassing these constituent modules. To achieve certain required deformation modes and mechanical properties, the modules are usually linked to form a mobile mechanism or a deformable structure. Here we present a novel 3D modular metamaterial constructed of hinged blocks, which utilizes both to realize alterable Poisson’s ratio and multi-stability. We demonstrate through theoretical analysis and experiments that upon axial compression, a single unit of the new metamaterial has two distinct mechanism motion stages with positive and negative Poisson’s ratio, respectively. And in between there exist a structure deformation stage, thereby forming a mechanism-structure-mechanism transition with bi-stability. Both the magnitude of Poisson’s ratio and the energy needed to bypass the structure deformation stage is programmable through two design parameters. In addition, the single unit can be stacked axially to form a tubular metamaterial with progressive folding deformation mode and multi-stability.