A bidirectional quasi-zero stiffness metamaterial for impact attenuation

A reusable bidirectional quasi-zero stiffness metamaterial (BQZS-MM) with quasi-zero stiffness zones under compressive and tensile loads is proposed, which can be employed for bidirectional kinetic energy absorption and impact attenuation. The BQZS-MM is characterized by the parallel connection of positive stiffness components and negative stiffness components to generate the BQZS. At the unit level, the bidirectional BQZS characteristics are analyzed theoretically and validated by simulations. The research further discusses the span and amplitude of the quasi-zero stiffness zone with structural parameters and serial-parallel mechanisms. The effect of quasi-zero stiffness zone' span and amplitude on dynamic performance is investigated. The physical prototypes are manufactured by selective laser sintering technology. The BQZS and reusability characteristics of BQZS-MM are examined by three repeated tensile and compressive tests. In comparison to existing metamaterials with bidirectional negative stiffness in one principal direction, under compressive and tensile loads, energy absorption, specific energy absorption, energy density, and crushing force efficiency of BQZS-MM have been significantly improved. During dynamic analysis, BQZS-MM attenuates bidirectional response acceleration peaks and achieves bidirectional impact attenuation. However, existing metamaterial with unidirectional quasi-zero stiffness can only achieve unidirectional impact attenuation. The BQZS-MM features novel BQZS mechanical characteristics, serving as a guide for creating brand-new buffer energy absorbers.