Author： Bescond C. Audoin B. Deschamps M. Qian M.
Publisher： S. Hirzel Verlag
ISSN： 0001-7884
Source： Acta Acustica, Vol.88, Iss.1, 2002-01, pp. : 50-58
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Abstract
A scanned line source-point receiver technique, based on laser generation and detection of acoustic waves, is used to measure the stiffness coefficients of anisotropic materials. Through transmission experiments are considered in which a laser interferometric probe is focused on the rear surface of the plate. The line source scanning direction and the normal of the plate define the plane of observation of the acoustic bulk waves. The measurements of sets of group velocities in several planes of observation, including principal and non principal planes of symmetry, are required to identify the nine stiffness coefficients of a medium exhibiting an orthotropic symmetry. The focusing effects that anisotropy gives rise to lead to a folded shape of the wave fronts. It is shown that advantage can be taken of this for the purpose of stiffness identification. Experiments are performed on a silicon sample to demonstrate the method accuracy, and uncertainties are evaluated by a numerical analysis of the group velocity data.
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