Design and Experimental Verification of a Broadband Multiphase Pentamode Material

Abstract

Pentamode material (PM) possesses great potential in underwater acoustic metamaterial device applications due to its broadband and solid-state merits. Previously proposed PM devices are all designed with single materials, where the additional weights for mass adjustment are connected directly to the struts for modulus adjustment. The coupling effects between them severely restrict available fabrication techniques and the realizable range of physical properties of PM devices. A multiphase PM configuration, the additional weights of which are bonded to the struts with interconnecting materials, is proposed, and a waterlike multiphase PM device based on the proposed configuration is developed to assess the validity of the multiphase PM configuration. It is revealed from both simulation and experimental results that the acoustic properties of the proposed multiphase PM device mimics water within the simulation frequency range of 3--24 kHz. The fabrication cost of the proposed multiphase PM device is reduced by 80%, and the duration is only 1/15 when compared to that of a single-phase PM device. Additionally, the multiphase PM has great advantages over single-phase PM for aspects such as withstanding higher hydrostatic pressure due to much more uniform stress distribution and broadening the realizable range of physical properties of PM devices significantly.