Application of the ultrasonic characterization methods for highly attenuating plastic materials

In this paper, prediction of the back surface reflection, which is based on attenuation and phase velocity dispersion estimation method, in highly attenuating plastic (polyvinylidene fluoride—PVDF) has been described. Estimation of the attenuation law is based on the inverse transfer function of the object approximation in the frequency domain. The oscillating character of the inverse transfer function of the highly attenuating plastic material gives rise to an ill-posed problem for approximation. It has been solved in two ways: application of the Tikhonov regularization process and iterative adjustment of the approximation parameters. The estimated attenuation coefficient α₀ and power n have been used for calculation of phase velocity dispersion using the Kramers–Kronig relations and having attenuation coefficient measured at single-frequency value.The reconstructed waveforms of the ultrasonic back surface reflections using the estimated attenuation and phase velocity dispersion curves have been presented and compared with the experimental one.