Recent advances in resonant ultrasound spectroscopy (RUS) for the measurement of the stiffness tensor of anisotropic and attenuative materials

Abstract

The elasticity tensor of a small sample of anisotropic material can be advantageously determined with Resonant Ultrasound Spectroscopy (RUS). In RUS, resonant frequencies of a sample are measured, and computed frequencies of a numerical model of the sample are fitted, yielding the stiffness tensor. RUS was developed in the 1990s, but until recently, it was in practice limited to measure materials with a high quality factor. We have recently adapted the method to measure attenuative materials such as plastics and hard biological tissues (bone and tooth tissues) with a typical quality factor of about 25. Our strategy combines Bayesian methods to retrieve overlapped resonant peaks in the RUS spectra and to solve the inverse problem using a limited number of resonant frequencies. The method allows a quasi-automated processing of RUS spectra where it is not necessary to know a priori the pairing between measured and computed frequencies. In the last years, we have extensively used RUS to document the anisotrop...