Characterization of a cylindrical rod by inversion of acoustic scattering data

• New technique proposed for nondestructive characterization of isotropic materials.
• Density and elastic constants measured from scattering data on rod-shaped samples.
• New technique was experimentally verified on steel and aluminum samples.
• It was shown that it can measure elastic constants of embedded fibers too.
• A perturbation study was conducted to verify the sensitivity of the technique.

In this paper, a new approach is proposed for nondestructive characterization of immersed and embedded isotropic rod-shaped samples by inversion of acoustic scattering data. The normal mode expansion technique is used for modelling the scattered field and the compression incident and compression scattered waves are considered. Genetic algorithm is the inversion technique used for estimating the elastic wave velocities and density of the rods from their measured backscattered pressure spectrum. The inversion technique is capable of computing the parameter values that best fit a particular set of data. A perturbation study is conducted on the sensitivity of the resonance frequencies to changes in elastic properties and density of the rods. The numerical results indicate that proper selection of resonance frequencies leads to accurate measurement of elastic constants and density. The proposed approach showed very good convergence and the results obtained were found to agree very well with available data.