Characterization of Immersed Transversely Isotropic Rods by Inversion of Acoustic Scattering Data

Elastic constants of cylindrical rods can be measured from their backscattered pressure spectrum when they are illuminated by an ultrasonic wave. This study provides an investigation into the measurement of elastic constants of a transversely isotropic rod using this technique. The proposed approach includes a mathematical model for the scattering process, experimental measurements on a transversely isotropic rod, and an inversion procedure for matching the mathematical and experimental data. This approach can be used for characterizing rods, wires, and whiskers used in fiber-reinforced composite materials. Such cylindrical components are usually transversely isotropic due to the processes used in their production. The normal mode expansion technique is used for modeling the scattered field. The measurements are done on a 4-mm diameter aluminum rod drawn from an isotropic 8-mm rod. The measured elastic constants of the drawn specimen confirm its transversely isotropic properties. The measured elastic constants are found to agree very well with available data.