Title: Medium characterization from interface-wave impedance and ellipticity using simultaneous displacement and pressure measurements
Authors: van Dalen, K. N ×
Drijkoningen, G. G
Smeulders, D. M. J
Heller, H. K. J
Glorieux, Christ
Sarens, B
Verstraeten, Bert #
Issue Date: Sep-2011
Publisher: American Institute of Physics for the Acoustical Society of America
Series Title: Journal of the Acoustical Society of America vol:130 issue:3 pages:1299-1312
Abstract: The interface-wave impedance and ellipticity are wave attributes that interrelate the full waveforms as observed in different components. For each of the fluid/elastic-solid interface waves, i.e., the pseudo-Rayleigh (pR) and Stoneley (St) waves, the impedance and ellipticity are found to have different functional dependencies on Young's modulus and Poisson's ratio. By combining the attributes in a cost function, unique and stable estimates of these parameters can be obtained, particularly when using the St wave. In a validation experiment, the impedance of the laser-excited pR wave is successfully extracted from simultaneous measurements of the normal particle displacement and the fluid pressure at a water/aluminum interface. The displacement is measured using a laser Doppler vibrometer (LDV) and the pressure with a needle hydrophone. Any LDV measurement is perturbed by refractive-index changes along the LDV beam once acoustic waves interfere with the beam. Using a model that accounts for these perturbations, an impedance decrease of 28% with respect to the plane wave impedance of the pR wave is predicted for the water/aluminum configuration. Although this deviation is different for the experimentally extracted impedance, there is excellent agreement between the observed and predicted pR waveforms in both the particle displacement and fluid pressure. (C) 2011 Acoustical Society of America. [DOI: 10.1121/1.3605537]
ISSN: 0001-4966
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Soft Matter and Biophysics
× corresponding author
# (joint) last author

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