Ultrasonic guided-waves characterization with Warped Frequency Transforms

Author

De Marchi, L. ; Caporale, S. ; Speciale, N. ; Marzani, A.

Author_Institution

Dept. of Electron., Comput. Sci. & Syst., Univ. of Bologna, Bologna

fYear

2008

fDate

2-5 Nov. 2008

Firstpage

188

Lastpage

191

Abstract

In this work a new time-frequency procedure for the extraction of multimodal and dispersive guided waves (GWs) from a recorded time-waveform is presented. The proposed ldquoWarped Frequency Transformrdquo (WFT) is based on a time-frequency domain tiling chosen to match the spectro-temporal structure of the different propagating guided waves by selecting an appropriate warping map which generates non-linearly frequency modulated atoms. The WFT transformation is fast, invertible, covariant to group velocity-delay shifts and, in force of the more flexible tiling, presents enhanced modes extraction capabilities. An application to Lamb Waves propagating in an isotropic plate is presented to show the potential of the proposed procedure.

Keywords

aluminium; discrete Fourier transforms; frequency modulation; plates (structures); structural acoustics; surface acoustic waves; time-frequency analysis; ultrasonic dispersion; ultrasonic propagation; Al; Lamb wave propagation; WFT transformation; appropriate warping map; dispersive guided waves extraction; inverse discrete-time Fourier transform; isotropic aluminum plate; multimodal waves extraction; nonlinearly frequency modulated atoms; spectro-temporal structure; time-frequency procedure; ultrasonic guided-wave characterization; velocity-delay shifts; warped frequency transform; Acoustic materials; Acoustic propagation; Acoustic waveguides; Computer science; Discrete Fourier transforms; Dispersion; Fourier transforms; Frequency modulation; Structural engineering; Time frequency analysis; Group-delay Covariance; Lamb Waves; Time-Frequency Representations; Warped Frequency Transforms;

fLanguage

English

Publisher

ieee

Conference_Titel

Ultrasonics Symposium, 2008. IUS 2008. IEEE

Conference_Location

Beijing

Print_ISBN

978-1-4244-2428-3

Electronic_ISBN

978-1-4244-2480-1

Type

conf

DOI

10.1109/ULTSYM.2008.0046

Filename

4803296