### ASA 127th Meeting M.I.T. 1994 June 6-10

## 3aPA9. A lumped-parameter model for the acoustic power output from a
vibrating body.

**John B. Fahnline
**

**
Gary H. Koopmann
**

**
**
*Ctr. for Acoust. and Vib., 157 Hammond Bldg., Penn State Univ., University
Park, PA 16802
*

*
*
A general lumped-parameter model for the acoustic power radiated by a
vibrating body is derived. The derivation starts from an analytical expression
for the acoustic power output written in terms of the Green's function of the
second kind and the specified surface velocity. By discretizing this expression
in terms of elemental volume velocities and ``averaged'' Green's functions, a
consistent approximation for the power output from a vibrating body is
determined. The approximation assumes that two solutions for the power output
from a vibrating body are equivalent if they have the same volume velocity
distribution over each of the surface elements. The limitations of the
approximation are examined and it is shown through several example problems
that the approximate expression for the power output is accurate as long as
each of the surface elements is small compared to both the acoustic and
structural wavelengths.