A general strategy for performance enhancement of negative stiffness mechanical metamaterials

Negative stiffness mechanical metamaterial possesses many interesting properties but fairly low strength. Introducing filler appears to be an effective strategy to enhance the cellular materials' mechanical properties. In this work, we show how to improve the mechanical properties of the cylindrical negative stiffness structure via introducing filler. We first offer the principle of the negative stiffness material combined with an alternative mechanism and then further investigate the mechanical response of the filler-free structure and the filled structure with different filler. We demonstrate that the linear elastic filler can improve the energy absorption but degrade the energy dissipation performance. The visco-hyperelastic filler can enhance the energy dissipation of the structure whether the snap-back behavior exists or not. The true negative stiffness filler can improve the structure's energy dissipation and decrease the strength simultaneously. The presented methods can be seen as a reference to the design of other negative stiffness mechanical metamaterials. • This work first comprehensively investigated the filled NS structure and provided new insight into the influence of the filler types on the mechanical properties of the filled cylindrical NS structures. • The presented theory for characterizing the filled and the unfilled cylindrical NS structures' mechanical response is of universality and lays the groundwork for future research on other filled NS metamaterials. • A novel strategy, harnessing the true NS filler to improve the NS structure's energy dissipation capacity, is first proposed and verified. • Research results demonstrate that the visco-hyperelastic filler can effectively improve the strength, energy dissipation, and absorption capacity, provided the equivalent stiffness of the filler is well matched with those of the cylindrical NS structure.