Prestrain-induced bistability in the design of tensegrity units for mechanical metamaterials

Tensegrity metamaterials are a type of artificial materials that can exploit the tunable nonlinear mechanical behavior of the constituent tensegrity units. Here, we present reduced-order analytical models describing the prestrain-induced bistable effect of two particular tensegrity units. Closed-form expressions of the critical prestrain at which a unit transitions into a bistable regime are derived. Such expressions depend only on the geometry of the units. The predictions of the reduced-order model are verified by numerical simulations and by the realization of physical models. The present results can be generalized to analogous units with polygonal base, and the proposed tensegrity units can be assembled together to form one-dimensional metamaterials with tailorable nonlinear features such as multistability and solitary wave propagation.