Modular multistable metamaterials with reprogrammable mechanical properties

Abstract

Owing to extensive potential applications in various engineering areas, the multistable metamaterials with remarkable mechanical properties have gained increasing interest from both academia and industry recently. However, the functionality of existing multistable metamaterials is hard to adjust once fabricated. To overcome the limitation, in this paper, we propose an idea of modular multistable metamaterial (MMM) with reprogrammable mechanical properties, which is assembled by unit cells with tunable snap-through behaviours. The unit cell is made by a dismountable bar and a fixed frame containing two bistable curved beams. By inserting the bar with different length into the frame, we can change the shape of curved beams and therefore tune the snap-through behaviour of the unit cell, which lies the foundation of its tunable multistabilities. We evaluate these tunabilities of geometry and mechanical properties of single unit cell by employing theoretical analyses and validate them by numerical simulations. The obtained quantitative results provide us the design guide for assembling of the MMM. We fabricate a certain number of components by 3D printing and assemble them as a unidirectional MMM to examine its reprogrammable macroscopic mechanical behaviours. We firstly investigate the tunable load–displacement responses experimentally and numerically; and then explore the tunable bandgaps through numerical simulations. Finally, we demonstrate the broader possibilities of assembly to form bi- and tri-directional, as well as gradient MMMs. The results presented in this paper have great significance for the design of modular metamaterials and expanding their application prospects in engineering structures.