Application of the through transmission ultrasonic technique for estimation of the phase velocity dispersion in plastic materials

Abstract

In many industrial applications through transmission ultrasonic measurements are widely used because they enable to perform characterization and long term monitoring of material properties. The waveform of the signal transmitted through the plastic object usually is distorted due to different factors, such as frequency dependent attenuation, phase velocity dispersion, diffraction, geometry of boundaries and etc. In order to increase the accuracy of ultrasonic measurements it is necessary to take into account these factors.
A few techniques have been applied in order to estimate the phase velocity dispersion in a planar PVDF plastic sample: estimation using the narrowband filtering and estimation from the phase spectra. Both of them gave similar results with a reasonable for practical applications accuracy.