A negative-stiffness based 1D metamaterial for bidirectional buffering and energy absorption with state recoverable characteristic

This study presented a novel negative-stiffness based metamaterial with the characteristics of buffering, energy absorption, and state recovery in two loading directions. The unit cell of the metamaterial is composed of cross-curve-beams (CCBs), supporting frames, and supporting beams. Through snap-through of the stable states of the curved beams, buffering, energy absorption and recovery of the initial state are fulfilled. The theoretical model of the negative stiffness (NS) unit cell is developed to quantify the mechanical feature and validated by finite element (FE) simulation. FE analysis has been done on the properties of the NS metamaterial structures composed of 1 × 1 × 1, 2 × 2 × 2 and 3 × 3 × 3 metamaterial unit cells under compression and tensile loads. Furthermore, quasi-static compression and tensile experiments are carried out on the three designed NS structures to verify the effectiveness of the simulation method and results. Meanwhile, the experimental and the simulation results demonstrate that the designed NS structures exhibit snap-through behavior and NS effect in both loading directions, so the structure can be used for bidirectional buffering and energy absorption. Repeated experiments also verify the designed NS structure has good state-recoverability and shock-resistance. • This study presents a novel negative-stiffness based metamaterial with the characteristics of buffering, energy absorption and the state recovery in two loading directions. • The theoretical model of the unit cell is developed to quantify mechanical property and validated by finite element (FE) simulation. • Quasi-static simulations and experiments results show that the NS structure under the tensile and compressive loads has snap-through behavior. • Repeated experiments are used to verify the reusability of the NS structure.