Acoustic radiation from a finite-length shell with non-axisymmetric substructures using a surface variational principle

S. H. Choi, Takeru Igusa, J. D. Achenbach

Research output: Contribution to journalArticle

Abstract

A modal-based method is developed to analyze the acoustic radiation of axisymmetric submerged shells of finite length with non-axisymmetric internal substructures, subjected to time-harmonic loads. In this method, a variational principle is used to derive impedance relations between the surface pressure and the surface velocity of the shell. These impedance relations are combined with the structural equations of motions based on a Lagrange energy formulation to form a complete set of equations for the fluid-structure interaction problem. Fourier series expansions are used to represent the circumferential dependence of the surface pressure and velocity. The method is demonstrated for two different configurations of substructures: circular ribs supporting length-wise beams and a spatially and modally dense array of oscillators. Since the substructures couple the circumferential modes, a large system of equations must be inverted. A matrix decomposition technique is used to reduce the size of the system of equations of the first example. For the second example, the asymptotic limit for an infinite number of substructures is developed using an integral form for the substructure impedance. It is shown that the Monte Carlo simulations for the oscillator substructures converge to the asymptotic results. It is also shown that, below the ring frequency, oscillators can induce damping that is more effective in reducing far-field radiation than high loss factors in the shell.

Original languageEnglish (US)
Pages (from-to)329-350
Number of pages22
JournalJournal of Sound and Vibration
Volume197
Issue number3
DOIs
StatePublished - Oct 31 1996
Externally publishedYes

Fingerprint

variational principles
substructures
sound waves
Acoustics
Radiation
Fluid structure interaction
oscillators
Fourier series
impedance
Equations of motion
Damping
Decomposition
series expansion
far fields
equations of motion
damping
harmonics
decomposition
formulations
fluids

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Acoustics and Ultrasonics
  • Mechanical Engineering

Cite this

Acoustic radiation from a finite-length shell with non-axisymmetric substructures using a surface variational principle. / Choi, S. H.; Igusa, Takeru; Achenbach, J. D.

In: Journal of Sound and Vibration, Vol. 197, No. 3, 31.10.1996, p. 329-350.

Research output: Contribution to journalArticle

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