Resonant ultrasound spectroscopy for anisotropic materials with misaligned geometric and material axes

Abstract

Resonant ultrasound spectroscopy (RUS) is a powerful non-destructive technique used to measure the full elastic tensor of a material. The original formulation of this technique has restrained its application to relatively simple situations in which the sample has a trivial geometry (e.g., cube, cylinder, sphere), is made of one material only, with perfect alignment of material and geometric axes. In many practical applications, these ideal conditions cannot be met. Recently, RUS has been enhanced by the authors to handle these more complex systems by combining the finite-element method with a genetic algorithm. The capabilities of this new RUS approach are demonstrated experimentally using both a non-uniform hemisphere and a cylindrical sample made of compressed particles. The particular manufacturing process of the cylindrical part results in a sample with anisotropy and a misalignment of the geometric and material axes. Although the sample has a simple geometry it consist of a complex material. Confidence in the RUS inversion process is assured by a careful comparison of the mode shapes measured experimentally and simulated with the proper material orientation and elastic tensor.