SEDL / STP / STP1169-EB / STP17966S

Wave Attenuation in Fiber-Reinforced Composites

Mal, AK
Professor and graduate student, University of California, Los Angeles, CA

Bar-Cohen, Y
Principal investigator, Nondestructive Evaluation, Douglas Aircraft CompanyJet Propulsion Laboratory, Long BeachPasadena, CACA

Lih, S-S
Professor and graduate student, University of California, Los Angeles, CA

Pages: 17    Published: Jan 1992

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Abstract

Attenuation of waves in graphite/epoxy composite laminates is studied through an ultrasonic experiment and theoretical analysis of the recorded waveforms. The specimens are immersed in water, insonified by a beam of acoustic waves from a broadband transducer, and the reflected signals are recorded by a second transducer in a pitch-catch arrangement. The received signals are analyzed by means of a theoretical model in which the composite is assumed to be a transversely isotropic and dissipative medium. A simple model of dissipation is proposed and calculations based on wave propagation in the laminate are carried out. The values of the damping parameters are determined through comparison between the measured and calculated waveforms of the reflected signal. Results are presented for four unidirectional specimens of different thicknesses. The assumed model of attenuation is shown to yield excellent agreement between measured and calculated waveforms in all four cases.