Accession Number : AD0837966

Title :   COUPLING OF ACOUSTIC FIELDS AND VIBRATING MEMBRANES AND PLATES.

Descriptive Note : Rept. for 1 Jul 67-31 Jan 68,

Corporate Author : GENERAL DYNAMICS GROTON CT ELECTRIC BOAT DIV

Personal Author(s) : Irgens, F. ; Brand, R. S.

Report Date : 01 JUL 1968

Pagination or Media Count : 57

Abstract : The report presents a general method for solving the problem of steady-state vibrations of an elastic plane structure set in an infinite rigid wall and surrounded by a fluid medium. The method is based on a normal mode procedure and the integral transform technique. The displacement function for the structure is assumed in the form of a normal mode series and the modal amplitudes may be evaluated from a truncated infinite set of linear algebraic equations. The effect of the fluid on the structure is given in terms of modal acoustic impedance coefficients. These coefficients are presented as double integral formulas which depend only on the mode shape functions and the parameter ka = (omega)a/c. The radiated acoustic pressure at any point in the fluid is given in a general formula containing the modal amplitudes and certain double integrals that must be evaluated numerically. The general method has been applied to a circular membrane subjected to uniformly distributed dynamic load. The surrounding medium is air on both sides of the membrane in one case and water on one side and air on the other in another case. The calculations have been carried out for a series of frequencies up to and beyond the fundamental frequency for the membrane. (Author)

Descriptors :   *SOUND TRANSMISSION), (*VIBRATORS(MECHANICAL), UNDERWATER SOUND, RESONANT FREQUENCY, MEMBRANES, METAL PLATES, LOADS(FORCES), VIBRATION, DAMPING, ELASTIC PROPERTIES, WATER, AIR, FOURIER ANALYSIS, INTEGRAL TRANSFORMS, COMPUTER PROGRAMS, INTERACTIONS.

Subject Categories : Acoustics
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE