M. A. Breazeale
Natl. Ctr. for Physical Acoust., Univ. of Mississippi, University, MS 38677
Harmonic generation in a carbon-fiber-epoxy-resin composite has been measured as a function of frequency between 4.0 and 8.5 MHz. The amplitudes of both the fundamental and the generated second harmonics were measured absolutely with a capacitive receiver at room temperature. Phase velocities also were measured. Dispersion is seen in the conventional nonlinearity parameter, but not in the phase velocity. The composite sample is highly attenuative and may have additional nonlinear terms that are not yet accounted for theoretically. Since the conventional nonlinearity parameter is defined for a lossless solid, data interpertation is unclear at present.