Programmable and multistable metamaterials made of precisely tailored bistable cells.

[Display omitted] • A system inverse design framework based on optimized bistable cells for constructing programmable multistable mechanical metamaterials is proposed. • Customized bistable cells with precise control of maximum instability force were designed using sensitivity-free topology optimization method. • According to the proposed design strategy, a programmable mechanical metamaterial with various target functionalities and deformation models has been developed. • Finite element analysis and experiments were used to demonstrate the specific complex deformations of the metamaterial. This study proposes a systematic inverse design framework for constructing multistable mechanical metamaterials with programmable gradients. Herein, we designed the tailored bistable cells with precisely controlled maximum instability forces through the topology optimization approach. Then, the designed bistable structures were programmed to construct the multistable mechanical metamaterials with different target gradient snapping sequences and deformation models. Consequently, the simulation and experimental results showed the feasibility of the design method, which successfully produced two- and three-dimensional mechanical metamaterial structures with different functions. Finally, we verified the expected deformation sequences and multistable behaviors of mechanical metamaterials by testing the designed specimens prepared via additive manufacturing. Overall, our findings show that the proposed design strategy offers a new paradigm for developing precisely tailored and programmable mechanical metamaterials. [ABSTRACT FROM AUTHOR]