Hybrid meta-structure for broadband waterborne sound absorption

Abstract

A new hybrid-mechanism metastructure combined resonances of locally resonant scatterers and air cavities is proposed for broadband waterborne sound absorption. In the design, the locally resonant scatterers are embedded into the backing plate of a rubber layer with air cavities. The results demonstrate significant absorption improvement in the low-frequency range using the locally resonant scatterers. Cavities of mixed sizes and locally resonant scatterers of mixed types can be used to achieve efficient absorption over an ultrawide band. This broadband absorption is found to be attributed to the hybrid-mechanism of the resonances of the cavities and the locally resonant scatterers. Furthermore, the absorption mechanism is illustrated by the displacement patterns, the absorption contribution decomposition analysis, and the effective medium theory.