Acoustic scattering by laminated plates with viscoelastic layers

Abstract

The effect of addition of viscoelastic layers on the acoustic scattering quadrupoles near the trailing edge of composite plates is evaluated. For modelling of the viscoelastic material the complex modulus approach was used in combination with the frequency-temperature correspondence principle. The computation of laminate stiffness is based on Classical Lamination Theory. We employ a numerical method to compute the acoustic field scattered by finite elastic plates. Based on a Boundary Element Method, this procedure solves the Helmholtz equation subject to boundary conditions related to the vibration of the plate. These conditions are recast in terms of the vibration modes of a rectangular plate. Results show that by adding viscoelastic plies to a composite plate we modify the far-field sound scattered by turbulence near an edge of the plate. Parametric studies show that this approach reduces scattered noise at resonance frequencies. Discussions on the operating temperature, positioning and thickness of the viscoelastic layers are provided