Extraction of Modulation laws of Elastic Shells by the use of the Wavelet Transform.

Ginette Saracco (1, 2) , Jean-Pierre Sessarego (1) , Jean Sageloli (1) , Philippe Guillemain (1) , Richard Kronland-Martinet (1)

1 LMA - Laboratoire de Mécanique et d'Acoustique [Marseille]
2 CEREGE - Centre européen de recherche et d'enseignement des géosciences de l'environnement

This paper isconcerned with the characterization of elastic targets immersed in a fluid and submitted to an acoustic impulse. Time-frequency methods have already been used in the case of scatterers of simple geometric shape. We have chosen the wavelet transform for its particular properties, such as linearity and local analysis at Df/f=Cst. We have developped an algorithm based on the behavior of the phase of the transform, which enables us to extract modulation laws (related to the dispersion law of the phase velocity), even for close echoes. In the case of spherical elastic shells,we have applied this method to both experimental and simulated signals. We point out the good agreement between theoretical ans experimental results.

Mots clés: acoustic scattering; impulse source; phase velocity; group velocity; surface wave; ridge; squeleton; frequency modulation laws; continuous wavelet transform; time-scale analysis

Domaines: Acoustique [physics.class-ph]; Acoustique [physics.class-ph]

Ginette Saracco, Jean-Pierre Sessarego, Jean Sageloli, Philippe Guillemain, Richard Kronland-Martinet. Extraction of Modulation laws of Elastic Shells by the use of the Wavelet Transform.. Research Notes in Applied Mathematics, Masson-Springer, 1991, Wavelets and Applications, Ed Y. Meyer (Research Notes in Applied Mathematics, serie eds P.J. Ciarlet & J.L. Lions), pp.61-68. ⟨hal-00157768⟩