USA As Represented by Secretary of the Navy

Herbert M Berall

Guillermo C Gaunaurd

Kurt P Scharnhorst

An apparatus and method for determining the material properties characterizing a fluid contained in a cavity inside a solid comprises analyzing the resonances in the amplitude of elastic waves scattered by the cavity. Specifically, the resonance positions and their widths are used to determine the sound speed and the density of the cavity filler. The sound speed is found from the spacing between two consecutive overtones of any mode, which asymptotically becomes uniform for the higher-index overtones. The density is obtained from the width of any high order resonance and accordingly, all the information about the material composition of the filler is contained, and can be extracted, from the high-frequency asymptotic region.

Apparatus and process for determining the composition of fluid-filled

The shear absorption of a viscoelastic material is determined by directing acoustical energy at the viscoelastic material and sampling the backscattered signals that result when compressional waves propagate through the material and are scattered by either a fluid-filled or evacuated cavity contained therein. The backscattered signals are converted to a resonance amplitude versus frequency domain and the shear absorption of the viscoelastic material is determined from the frequency and the half-width of the resonance peaks.

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Bethesda, MD, United States of America

Herbert M Berall