Cellular Materials with Tunable Bistability integrating Prominent soft and stiff properties

Abstract

Breaking the traditional boundary between the soft and stiff materials is being urgently desired for engineering materials that are overburdened by the demands of complicated and versatile tasks. The realization of multistability through elaborate units has been demonstrated, but the trade-off between its performance and lightweighting across different states remains underdeveloped. In this work, we pioneer bridging the soft-stiff responsive strategy of lightweight cellular materials through architecturally nesting two materials with contrasting properties. The proposed cellular materials can be reconfigured and switched between soft and stiff states, as demonstrated experimentally, theoretically and numerically. The soft state represents high perturbation sensitivity and prominent vibration isolation properties. The stiff state achieves strong load-carrying capability due to multi-synergistic mechanisms, with the crushing modulus and strength 668.78 and 1037.55 times as high as that in the soft state in cases of soft materials embedded in metal materials, respectively. The manipulable mechanical properties can be tuned across a broad design space while maintaining robust switchability. These advantages of the proposed bistate cellular materials offer promising application prospects from adaptive protection to shock absorption and beyond.