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.