Experimental verification of latticed acoustic metamaterials with pentamode to bandgap characteristics

Pentamode and bandgap characteristics of metamaterials are of great significance to the control of elastic wave propagation by acoustic metamaterials. Pentamode metamaterials are artificially designed solid structures that exhibit fluid-like behavior. The bandgap characteristic of metamaterials effectively hinders the propagation of elastic waves. A latticed metamaterial with pentamode characteristics is proposed, achieving bandgap features by altering the positions of nodes between arms in the unit structures. This study aims to experimentally verify the pentamode and bandgap characteristics of acoustic metamaterials. Finite element analysis using COMSOL Multiphysics and underwater experiments with three models theoretically and experimentally validate the ability of latticed metamaterials to control elastic wave propagation under various parameters. By examining the band structure, the propagation of acoustic waves within the pentamode domain (10–20 kHz) for pentamode model and bandgap domain (5–10 kHz) for bandgap models are assessed. The experimental results agree with the theoretical simulations. The pentamode and bandgap characteristics of the latticed metamaterials have a broad development prospect in acoustic detection. Graphical abstract