Abstract:
Measurements of longitudinal phase velocity and rate of harmonic generation
(nonlinearity parameter) have been made in a laminate graphite-epoxy composite.
Both quantities are observed to be frequency dependent between 3.5 and 8 MHz.
The theoretical model of Van Den Abeele and Breazeale [J. Acoust. Soc. Am. 99,
1430--1437 (1996)] has been applied to the data. Including dispersion terms and
their nonlinear counterparts improves agreement over that obtained with the
theory used for single crystals. The origin of this difference probably is in
scattering from laminate boundaries. Some inadequacies still exist, however.
Their origin has not been established yet. [sup