Programmable mechanical metamaterials based on gear structures

The use of intelligent materials is anticipated in various fields such as medicine, science, and the military. In this context, the development of programmable metamaterials with in-situ continuously adjustable mechanical properties holds significant importance for the advancement of smart materials. Here we propose a novel approach to constructing mechanical metamaterials using gears as the fundamental building blocks. The gear-based metamaterials we introduce is a multi-stable structure that allows for seamless transitions between stable states by engaging the gear teeth. This unique feature enables the metamaterials to possess in situ continuously adjustable mechanical properties, including a wide range of compressive Young's modulus, variable generalized shear stiffness, and tunable dynamic characteristics of the system, and both simulations and experiments are used to validate the metamaterial designs. These unique properties of gear-based metamaterials offer a novel path to creating programmable metamaterials with in situ continuously tunable mechanical properties. • Gear-based mechanical metamaterials behave as multi-stable metamaterials. • A gear metamaterial with strong robustness is proposed. • Gear-based mechanical metamaterials exhibit programmable mechanical properties and dynamic behavior. • The proposed metamaterial has outstanding application potential in stiffness adjustment and stability.