Coupled Scholte modes supported by soft elastic plates in water

Abstract

Localized acoustic surface waves supported by a "soft" elastic plate in water are explored. Unlike many materials, such as aluminum, for soft interfaces the Scholte wave, a localized interface wave, has a speed well below that of sound in water, and the energy of the Scholte wave is no longer mainly localized to the water. We note that the Scholte velocity is largely independent of Poisson's ratio in the solid, and rather than the bulk speeds of sound, the ratio between the Young's modulus and the density of the solid may better indicate whether an interface is soft. The behavior of the coupled Scholte modes along a thin plate with soft interfaces are investigated. It is demonstrated, and experimentally verified using acrylic plates underwater, that for soft interfaces, the symmetric coupled Scholte mode exhibits dispersive behavior, and deviates from the Scholte and the fluid velocities at low frequencies.

Elastic metasurfaces for Scholte–Stoneley wave control

“…Aside from structured interfaces, SSW also exists at the interface between 'soft' elastic plates in water. Notably, for soft materials, SSW presents a speed well below that of sound in water and is no longer mainly localized to the fluid [38].…”

Underwater Focusing of Sound by Umklapp Diffraction

“…At interfaces between two elastic solids there exist localized Stoneley waves and radiative leaky Rayleigh waves [3,4]; special cases of Stoneley waves exist at fluid-solid interfaces that are often called Scholte waves [5,6]. For thin elastic plates submerged in a fluid the Scholte modes on either interface can couple, displaying dispersive behavior at low frequencies [7]. These interfacial waves are analogous to electromagnetic surface plasmons [8] in that they exist independently of any periodic structuring.…”