Pentamode metamaterials with ultra-low-frequency single-mode band gap based on constituent materials

An effective method for realizing ultra-low-frequency single-mode band gap in pentamode metamaterials is proposed based on constituent materials. Results show that the decreasing ratio E/rho (stiffness/mass density) of constituent material can significantly lower the frequency range of single-mode band gap. By merely replacing the constituent material from Al to rubber, the center frequency f (c) of single-mode band gap can be reduced nearly 600 times (from 3621 Hz to 6.5 Hz), while the normalized bandwidth Delta f/f (c) and the ratio of bulk modulus B to shear modulus G of pentamode structure keep substantially stable. The nonlinear fitting demonstrates that the relation between f (c) and E/rho satisfies the logarithmic function. The two-component pentamode structure is designed to further explore the ultra-low-frequency single-mode band gap. The effects of thick-end diameter D of double-cone, diameter D (0) and material type of additional sphere, on single-mode band gap of two-component system are analyzed. This work is attractive for several similar to Hz acoustic/elastic wave regulations using pentamode metamaterials.

Automated summary

This study proposes an effective method for achieving ultra-low-frequency single-mode band gap in pentamode metamaterials based on constituent materials. It is found that decreasing the E/rho ratio of constituent material significantly lowers the frequency range of single-mode band gap, while other properties of the pentamode structure remain stable. By analyzing the effects of two-component system parameters, the formation mechanism of ultra-low-frequency single-mode band gap is further explored.