• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue

Dec 2007

Volume 122, Issue 6, pp. 3133-EL235

Return to All Sections
back to top
RSS Feeds

Acoustoelasticity in soft solids: Assessment of the nonlinear shear modulus with the acoustic radiation force

J.-L. Gennisson, M. Rénier, S. Catheline, C. Barrière, J. Bercoff, M. Tanter, and M. Fink

J. Acoust. Soc. Am. Volume 122, Issue 6, pp. 3211-3219 (2007); (9 pages) | Cited 7 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The assessment of viscoelastic properties of soft tissues is enjoying a growing interest in the field of medical imaging as pathologies are often correlated with a local change of stiffness. To date, advanced techniques in that field have been concentrating on the estimation of the second order elastic modulus (μ). In this paper, the nonlinear behavior of quasi-incompressible soft solids is investigated using the supersonic shear imaging technique based on the remote generation of polarized plane shear waves in tissues induced by the acoustic radiation force. Applying a theoretical approach of the strain energy in soft solid [ Hamilton et al., J. Acoust. Soc. Am. 116, 41–44 (2004) ], it is shown that the well-known acoustoelasticity experiment allowing the recovery of higher order elastic moduli can be greatly simplified. Experimentally, it requires measurements of the local speed of polarized plane shear waves in a statically and uniaxially stressed isotropic medium. These shear wave speed estimates are obtained by imaging the shear wave propagation in soft media with an ultrafast echographic scanner. In this situation, the uniaxial static stress induces anisotropy due to the nonlinear effects and results in a change of shear wave speed. Then the third order elastic modulus (A) is measured in agar-gelatin-based phantoms and polyvinyl alcohol based phantoms.
Show PACS
43.25.Dc Nonlinear acoustics of solids
43.25.Ed Effect of nonlinearity on velocity and attenuation

A two-dimensional pseudospectral model for time reversal and nonlinear elastic wave spectroscopy

Thomas Goursolle, Samuel Callé, Serge Dos Santos, and Olivier Bou Matar

J. Acoust. Soc. Am. Volume 122, Issue 6, pp. 3220-3229 (2007); (10 pages) | Cited 4 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
One way to characterize metallic materials in the presence of defects like dislocation networks is to measure their large dynamic nonlinear elastic response. In this numerical study, a new method combining the nonlinear elastic wave spectroscopy (NEWS) method with a time reversal (TR) process is proposed. This method, called NEWS-TR, uses nonlinear analysis as a pretreatment of time reversal and then consists of retrofocusing only nonlinear components on the defect position. A two-dimensional pseudospectral time domain algorithm is developed here to validate the NEWS-TR method as a potential technique for damage location. Hysteretic nonlinear behavior of the materials being studied is introduced using the Preisach-Mayergoyz model. Moreover, in order to extend this solver in two dimensions, the Kelvin notation is used to modify the elastic coefficient tensor. Simulations performed on a metallic sample show the feasibility and value of the NEWS-TR methodology for microdamage imaging. Retrofocusing quality depends on different parameters such as the filtering method used to keep only nonlinear components and the nonlinear effect measured. In harmonic generation, pulse inversion filtering seems to be a more appropriate filtering method than classical harmonic filtering for most defect positions, mainly because of its ability to filter all fundamental components.
Show PACS
43.25.Dc Nonlinear acoustics of solids
43.40.Le Techniques for nondestructive evaluation and monitoring, acoustic emission
43.60.Tj Wave front reconstruction, acoustic time-reversal, and phase conjugation

Accelerometer measurements of acoustic-to-seismic coupling above buried objects

Keith Attenborough, Qin Qin, Jonathan Jefferis, and Gary Heald

J. Acoust. Soc. Am. Volume 122, Issue 6, pp. 3230-3241 (2007); (12 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The surface velocity of sand inside a large PVC container, induced by the sound pressure from either a large loudspeaker radiating into an inverted cone and pipe or a Bruel and Kjaer point source loudspeaker mounted with its axis vertical, has been measured using accelerometers. Results of white noise and stepped frequency excitation are presented. Without any buried object the mass loading of an accelerometer creates resonances in the spectral ratio of sand surface velocity to incident acoustic pressure, i.e., the acoustic-to-seismic (A/S) admittance spectra. The A/S responses above a buried compliant object are larger and distinctive. The linear A/S admittance spectra in the presence of a buried electronic components box have been studied as a function of burial depth and sand state. The nonlinear responses above the buried box have been studied as a function of depth, sand state, and amplitude. Predictions of a modified one-dimensional lumped parameter model have been found to be consistent with the observed nonlinear responses. Also the modified model has been used to explain features of the A/S responses observed when using an accelerometer without any buried object.
Show PACS
43.25.Jh Reflection, refraction, interference, scattering, and diffraction of intense sound waves
43.25.Dc Nonlinear acoustics of solids
43.20.Gp Reflection, refraction, diffraction, interference, and scattering of elastic and poroelastic waves
43.25.Zx Measurement methods and instrumentation for nonlinear acoustics
Return to All Sections
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close