Negative stiffness mechanical metamaterials based on curved beams for reusable shock isolation

Previous studies on negative stiffness mechanical metamaterials have mainly focused on their quasi-static mechanical properties, while studies on their dynamic mechanical properties are relatively scarce. As energy-absorbing materials, the energy absorption mechanism of negative stiffness metamaterials differs from that of traditional materials, which rely on viscoelastic effects, plastic deformation, or fracture damage. In the process of energy absorption, negative stiffness metamaterials can convert external input mechanical energy into structure strain energy, so they can provide good protection against external impact objects during dynamic impact. This paper aims to comprehensively and systematically study the general law of the buffering behavior of negative stiffness metamaterials based on curved beams through the design of buffering experiments and the establishment of an evaluation scheme for buffering performance, reveal its buffering mechanism under dynamic loads, and evaluate the effects of different geometric parameters for curved beam units and series unit cell number on metamaterial buffering performance. The results show that the proposed negative stiffness metamaterial based on curved beam exhibits good energy absorption capacity under quasi-static loading and excellent buffering capability under dynamic impact loads. Moreover, it only undergoes elastic deformation during the deformation process and is reusable.