Simultaneous measurement of speed, attenuation, thickness and density with reflected ultrasonic waves in plates

This paper presents a method to measure simultaneously the velocity and the attenuation of ultrasonic waves, the density and the thickness of the sample. Velocity and thickness are deduced from time-of-flight. The Fourier transform of all acquired ultrasonic echoes furnishes the experimental transfer function. This is combined with the expression of plate reflection coefficient to build a form of which the minimum corresponds to the best estimate of density and longitudinal wave attenuation. Results are obtained for epoxy matrix reinforced by long glass fibers composite materials