Remorphable Architectures: Reprogramming Global Bistability through Locally Bistable Metamaterials

Abstract

Bistability enables a physical system to reversibly transition between two stable states via snapping instability, and is broadly classified as either global-facilitating macroscopic shape morphing of a structure-or local, which enables internal geometric reconfiguration within a metamaterial. In existing metamaterials and structures, each form of bistability is implemented independently from the other, failing to capitalize on the benefits that their interaction can offer. In this work, locally bistable metamaterials are integrated into a globally bistable structure, enabling reprogrammable global bistability. By selectively transitioning local unit cells of the metamaterial into a self-contact state, a specific combination of soft hinges is encoded into the global structure. The encoded hinges can significantly alter the global kinematics of the structure, allowing reprogrammable triggering force, snapping trajectory, and energy barrier. Distinct combinations of local hinges are shown to enable a metamaterial arch to deliver multi-target actuation, a linkage to switch seamlessly between multistable, bistable, and monostable states, and a dome to transform into various curved shapes. The local-to-global interplay unveiled in this work can be leveraged to design multi-modal jumping/leaping robots and space structures capable of dynamically adjusting their actuation and morphing modes by simply flipping the local states of their unit cells.