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

Abstract

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 ∼ 104). Especially when the thin-end diameter of core-double-cone is smaller, the B/G ratio exceeds 6 × 104, 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.