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.