Computational design of multistable metamaterials

Metamaterials’ properties arise not only from their chemical composition, but mainly from their periodic structure. While most of these materials are characterized by a fixed geometry, some materials are designed with internal hinging mechanisms. This allows them to be reconfigured with external stimuli, therefore exhibiting tuneable properties. However, these materials become dependent on the stimuli, and once removed the material will relax to the initial configuration. Previously we proposed a design strategy based on space-filling extruded polyhedra to create 3D reconfigurable materials comprising a periodic assembly of rigid plates and elastic hinges. Interestingly, for some of these structures we found additional stable configurations that are spatially admissible, but that cannot be reached without temporarily deforming the rigid faces. Here, we soften this constraint to open up new folding pathways. We introduce a computational approach to scan the energy landscape of these complex 3D structures, and show that our method closely mimics experimental implementations of locally actuated metamaterials. Using this approach, we find a wealth of multistable unit cells that can be assembled to create responsive materials capable of switching between different properties.