Signal response of elastically coated plates

Abstract

An analytical model of a compliant elastic coating attached to a submerged thin plate has been developed. A plane acoustic wave, representing the signal, is incident from the water on to the elastic coating. The normal and tangential velocity components induced in the coating by the acoustic wave are calculated. The effects of incidence angle, frequency, location throughout the coating, and coating properties on the signal response velocity components are evaluated. Many details of the coating velocity components are explained based on simple uncoupled waveguide characteristics of the coating. In general, the normal velocity components are several tens of decibels higher in amplitude than the tangential velocity components. It was shown, however, that the tangential velocity component could be increased by an average amount of about 20 dB, without serious degradation of the normal component, by altering the coating properties. In particular, combinations of high longitudinal wave speed and low shear wave speed were found to be advantageous.

An exact elasticity model for rib-stiffened plates covered by decoupling acoustic coating layers

“…Previously published researches have mainly focused on the unreinforced plates coated by decoupling acoustic coating layers [1][2][3][4][5][6][7]. There are also numerous researches regarding with the reinforced structures [12][13][14][15][16][17][18][19][20][21][22], while which are not covered by decoupling acoustic coating layers.…”

“…As an effective passive control approach, the addition of decoupling acoustic coating layers on resonant structures is commonly applied to reduce the vibration and noise radiation by the structures immersed in fluids [1][2][3][4][5][6][7]. The purpose of this treatment is to isolate the vibrating structure from the surrounding fluids.…”

“…Also, in the category of 2D plane strain elasticity theory, Ko [3] developed a theoretical model to evaluate the reduction of structure-borne noise from an infinite plate coated with an air-voided elastomeric baffle. In conjunction with the thin-plate theory, Keltie [4] formulated an analytical model for a compliant elastic coating attached to a submerged thin plate, where the normal and tangential velocity components in the coating were detailed analyzed. Taking into account the attached distributed inhomogeneity, Zhang and Pan [5,6] established a theoretical model to investigate the sound radiation and absorption properties of coated infinite plates.…”

Sound radiation from a fluid-loaded infinite plate with a patch

“…Such study is also motivated by a proposal for attaching a finite signal conditioning plate, usually a high-impedance steel plate, to an elastically coated surface. 5 As the coated surface tends to be pressurereleased, 6 a signal conditioning plate placed on the surface may increase the local sound reflection and thus increase the signal-to-noise ratio of the pressure sensors for detecting incoming sound. A work that directly addresses such a problem was by Kirpichnikov and Romanova,7 who used a section of an infinite plate with a different thickness as a distributed inhomogeneity and studied the sound radiation due to the scattering of an incident structural wave by the inhomogeneity.…”

Underwater sound radiation from an elastically coated plate with a discontinuity introduced by a signal conditioning plate

“…Attaching an elastic coating to the outside surface of an underwater structure has become a common practice for reducing a structure's self-noise [1][2][3][4][5][6] and the reflection of incoming signals from active sonar. 7,8 The coating is usually acoustically soft and decouples the fluid in contact with the coating from motion in the base structure.…”