Ultrasonic Velocity Measurement in Viscoelastic Material Using the Wavelet Transform
Eduardo Moreno, Fabian Jose Obredor Garcia, Martha Castillo, Alejandro Sotomayor, Victor Castro, Martín Fuentes · Kluwer Academic Publishers eBooks · 2006
The measurement of the time propagation of ultrasonic pulses using techniques based on digital signal processing are now used like the Pulse-overlapping method. In this case there are the methods that use the Cross-Correlation Function (CCF) and Hilbert Transform (HT). However, for the case of viscoelastic material, it is not possible to apply this new methods, as a consequent of the viscoelastic dispersion. In this paper, we present a method based on the Continuous Wavelet Transform (CWT). Experiments were made in steel and acrylic. The results show no differences in steel and significant differences in acrylic as a viscoelastic material. In this last case the CWT shows better properties over the CCF and HT for the evaluation of time propagation. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.