Title: Anisotropy of the Frequency-Dependent Ultrasonic Attenuation in Unidirectional Graphite/Epoxy Composite
Material
Abstract:
Experimental results of the anisotropy of the frequency dependence of the ultrasonic attenuation in unidirectional graphite/epoxy composite
are presented. This material is made of graphite fibers aligned along a single axis and embedded in epoxy resin with a random transverse
distribution. The results show that for the 9 waves generated (3 longitudinal and 6 transverse) the signal loss was approximately linearly
dependent on frequency over the useful bandwidth of the measurement system. Thus, a least-squares line fit to the data divided by the total
propagation length in the sample provided the slope of attenuation. The slope of attenuation for longitudinal waves propagating parallel to
the fibers was substantially less than those with propagation perpendicular to the fibers. In contrast, for transverse waves, the slopes of
attenuation associated with either propagation or polarization parallel to the fibers were larger than those corresponding to both polarization
and propagation perpendicular to the fibers.
Author:
T.D. Lhermitte, S.M. Handley, M.R. Holland, and J.G. Miller,
Source:
Proc. IEEE Ultrasonics Symposium, 1992, Orlando, 91CH3079-1,
pp. 819-823,
(1992).
(C) 1995 Laboratory for Ultrasonics, Washington University in St. Louis
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Rolf Diederichs 10.Febr. 1996, info@ndt.net