Quantitative ultrasonic measurements in composite materials

This paper reviews several approaches for realizing quantitative ultrasonic measurements in composite materials. Both active and passive techniques are considered in which the signals are processed with either deterministic or neural-like, intelligent signal processing algorithms. The applications of such measurements include the characterization of acoustic sources and the determination of a composite material's frequency-dependent attenuation and wavespeeds. It is also shown how measurements of the arrival-times and amplitudes of various wave modes in anisotropic composite materials can be used to recover the matrix of the material's elastic constants and to generate an image of the material's anisotropy and its local variation.