Theoretical and Experimental Identification of Resonance Modes of Cylindrical Cavities in an Isotropic Solid Medium

In this paper, the equations of acoustic wave scattering from hollow or fluid-filled cylindrical cavities embedded in an isotropic elastic solid are derived and the normalized backscattered pressure spectrum (form function) is plotted. When the wave strikes the body of the cylindrical cavity, surface waves are formed on the periphery of the target. These surface waves circumnavigate the body of the cavity and at certian frequencies interfere constructively and build up to the circumfrerencial resonance modes of the cylindrical cavity. The resonance modes appear as sudden pressure drops in the form functoin. We propose a new method for identification of resonance modes of the cylindrical cavity. Measurements conducted on a cylidrical cavity machined in an aluminum block indicates that the resonance modes identified in the analytical model completely agree with those observed in experimental measurements