ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

3aSA4. Structural and acoustic intensity analysis for a fluid-loaded elastic plate with a distributed inhomogeneity.

J. M. Cuschieri

Ctr. for Acoust. and Vib., Dept. of Ocean Eng., Florida Atlantic Univ., Boca Raton, FL 33431

D. Feit

David Taylor Res. Ctr., Bethesda, MD 20084

The solutions developed for the response and scattered pressure from a fluid-loaded plate with a distributed mass inhomogeneity, which were presented at the ASA 128th meeting in Austin, Texas, are extended to included distributed stiffness inhomogeneities. The same four types of distributions, with varying degrees of ``smoothness'' are considered for the stiffness distribution. The scattering characteristics between the mass and stiffness inhomogeneities are different, and while the scattering is dipolelike for the mass inhomogeneity, it is quadrupolelike for the stiffness inhomogeneity. The results for this presentation are presented in the form of structural and acoustic intensity maps, both as vector plots and streamline plots. For frequencies lower than the critical frequency of the fluid-loaded plate, the results show the constant exchange of power between the plate and the fluid. The streamline plots for the reactive intensity show a band very close to the plate surface. For higher frequencies, the characteristics of the intensity maps become dependent on the relative length and ``smoothness'' of the distributed inhomogeneity.