Demonstration of a broadband aqueous acoustic metasurface

• Published in: The Journal of the Acoustical Society of America 2017-05, Vol.141 (5), p.3574-3574
• Main Authors: Guild, Matthew D., Rohde, Charles, Martin, Theodore P., Orris, Gregory
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4987597

Acoustic metamaterials have been utilized in recent years to demonstrate extreme acoustic properties, such as those with negative or near-zero dynamic values. While effective, the use of acoustic metamaterials can lead to voluminous structures that may not be practical for some applications. Alternatively, ultrathin structures known as acoustic metasurfaces offer the same capability to achieve extreme properties as acoustic metamaterials while offering the added benefit of having negligibly small (i.e., subwavelength) thickness. In this work, we will discuss an aqueous acoustic metasurface that utilizes subwavelength structures designed to acoustically act in parallel, allowing for a thin, modular structure to be realized while achieving a broad range of effective surface properties. A theoretical formulation for the design of the flexural elements is presented, accounting for the elastic motion of the elements subject to fluid loading due to the water. Based on this design, an aqueous acoustic metasurface was constructed from a brass plate, which was machined to achieve the prescribed flexural elements on the surface, and experimentally tested in water. The results of this analysis and testing will be discussed. [Work supported by the Office of Naval Research.]