Core-shell pentamode metamaterials with broader mechanical response and higher sensitivity

Core-shell pentamode metamaterial is designed and its phonon band structure is calculated by finite element method. Influences of factors, including constituent material and dimensions of the core-double-cone, on the mechanical properties and single-mode band gap (i.e. single-mode frequency regime, in which only compression wave exists and shear waves are completely suppressed) of the core-shell pentamode metamaterials are systematically investigated based on the static continuum mechanics calculations. It's found that compared with the traditional non-core-shell pentamode metamaterial, the core-shell one has broader mechanical response and higher sensitivity (ratio of bulk modulus B to shear modulus G: B/G similar to 10(4)). Especially when the thin-end diameter d(c) of core-double-cone is smaller, the B/G ratio exceeds 6 x 10(4), which is nearly 54 times than that of non-core-shell structure. The smaller Young's modulus E-c of core material and the smaller dimension of core-double-cone will be conducive to obtain single-mode band gap with lower frequency and wider bandwidth.

Automated summary

The core-shell pentamode metamaterial outperforms the traditional non-core-shell structure in terms of mechanical properties and single-mode band gap, with broader mechanical response and higher sensitivity. The size of the core-double-cone and the Young's modulus of the core material play important roles in achieving a single-mode band gap with lower frequency and wider bandwidth.