Resonant ultrasound spectroscopy with large attenuation and arbitrary geometry

Abstract

Resonant ultrasound spectroscopy (RUS) is a powerful and established technique for measuring material properties. The first step of this technique consists of extracting resonance frequencies and attenuations from the vibrational frequency spectrum measured on a sample with free boundary conditions. An inversion technique is then used to retrieve the elastic tensor from the measured resonance frequencies. As originally developed, RUS has been mostly applicable to (1) weakly attenuating media where each resonance frequency can be clearly identified and (2) relatively simple geometries where analytical solutions exist. In this presentation, the possibility of using RUS in a highly attenuating medium and on a sample of arbitrary geometry is explored. The Kumaresan-Tufts algorithm is used to fit a sum of exponentially damped sinusoids with closely spaced frequencies to the measured frequency spectrum. The inversion of the elastic tensor is achieved with a genetic algorithm, which allows searching for a global minimum within a discrete and relatively wide solution space. The accuracy of the proposed approach is evaluated against numerical data for which the solutions are known a priori. [This work was supported by the U.S. Dept. of Energy, Fuel Cycle R&D, Used Fuel Disposition (Storage) campaign.]