Underwater sound radiation by a layered infinite elastic plate with discontinuity
The underwater sound radiation from layered structu re is determined by the properties of elastic waves in the structure and by interaction between structural/structur al waves and between structural/fluidal waves. In t his paper, a model of a layered infinite plate is used to addres s how the properties and interaction influence the near field and far field characteristics of the radiated sound. In par ticular, the effect of structural discontinuity int roduced to the layered plate by a finite signal conditioning plate on unde rwater sound radiation is investigated. The scatter ing of structural waves in the layered plate by the signal conditioni ng plate is used to explain the changes in the radi ated sound due to the discontinuity.
Acoustic radiation from an elastic baffled rectangular plate covered by a decoupling coating and immersed in a heavy acoustic fluid
The vibroacoustic behavior of an elastic, simply supported rectangular plate covered by a locally reacting decoupling layer supporting thickness deformation is presented. The model simulates the vibration and acoustic response of the system immersed in water and subjected to a point force disturbance. A simplified version of the theory is derived in the limiting case of a large decoupling (low mechanical impedance of the layer/high frequency). An appropriate vibratory indicator, representative of the acoustic attenuation provided by the decoupling treatment, and independent of the structure dimensions, is also investigated from the perspective of small-scale laboratory characterization.
Scattering of sound by a fluid‐loaded plate with a distributed mass inhomogeneity
The scattering of a plane acoustic wave by a fluid‐loaded, thin, elastic plate, of infinite extent, with a distributed mass inhomogeneity is investigated. Two approaches are presented, an iterative approach valid when a measure of the distributed impedance is much lower than that of the uniform fluid‐loaded plate, and a full numerical solution which while having no restricting assumptions is somewhat demanding computationally. For the iterative solution a set of correction terms is evaluated and applied to the response of the uniform plate with no inhomogeneities. The number of correction terms required is dependent on the relative magnitude of the inhomogeneity. In the full numerical solution, the presence of the distributed inhomogeneity in the equation of motion, when expressed in the wave‐number domain, results in a Fredholm integral equation of the third kind. By substituting for the product of the response and the plate characteristic equation (impedance), the Fredholm integral of the third kind is ...