Determination of All 21 Independent Elastic Coefficients of Generally Anisotropic Solids by Resonant Ultrasound Spectroscopy: Benchmark Examples

We present an experimental methodology for determination of all 21 elastic constants of materials with general (triclinic) anisotropy. This methodology is based on contactless resonant ultrasound spectroscopy complemented by pulse-echo measurements and enables full characterization of elastic anisotropy of such materials from measurements on a single small specimen of a parallelogram shape. The methodology is applied to two benchmark examples: a material with generally rotated cubic anisotropy (single crystal of silicon) and an isotropic material (silicon-infiltrated silicon carbide ceramics). In both the proposed approach is able to provide a full triclinic tensor with relatively low experimental errors and to identify indubitably the anisotropy class of the material; for the cubic material also the orientations of the principal axes and the cubic elastic coefficients are reliably determined.