ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

2aSA5. Acoustic scattering from a fluid-loaded elastic plate with a distributed inhomogeneity of varying length scales.

Joe M. Cuschieri

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

David Feit

David Taylor Res. Ctr., Bethesda, MD 20084

Solutions were presented at the 128th and the 129th ASA meetings for the response and acoustic scattering from a fluid-loaded elastic plate with a distributed mass or stiffness inhomogeneity. The distributions considered for the inhomogeneity were a uniform distribution, a quadratic distribution, and a biquadratic distribution. It was shown in the previous presentations that below the critical frequency, there is a marked difference in the scattering between a mass inhomogeneity and a stiffness inhomogeneity. Furthermore, the scattering from the stiffness inhomogeneities was much less than that from the mass inhomogeneities. Above the critical frequency, both types of inhomogeneities generated similar scattering results. In this paper the influence of variations within the distribution of the inhomogeneity is considered. That is, apart from the overall distribution, the inhomogeneity has local changes. The inhomogeneity has two length scales, one associated with the overall distribution, where the same types of distributions as previously are considered, and one associated with the changes within the inhomogeneity distribution. The scattering from stiffness-type inhomogeneities increases with the introduction of this second length scale, while the scattering from the mass inhomogeneities is less influenced by the introduction of the second length scale. These results agree with those presented by Steinberg and McCoy at the 129th ASA meeting. [Work sponsored by ONR.]