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Tensile stress acoustic constants of unidirectional graphite/epoxy compositesPreviously, the stress acoustic constants (SACs) of unidirectional graphite/epoxy composites were measured to determine the nonlinear moduli of this material. These measurements were made under compressive loading in order to obtain the sufficient number of values needed to calculate these moduli. However, because their strength in tension along fiber directions can be several times greater, most composites are used under tensile loading. Thus, it is important to characterize the nonlinear properties of these materials in tension as well. The SACs which are defined as the slope of the normalized change in ultrasonic 'natural' velocity as a function of stress were measured in a unidirectional laminate of T300/5208 graphite/epoxy. Tensile load was applied along the fiber axis with the ultrasonic waves propagating perpendicular to the fiber direction. Changes in velocity were measured using a pulsed phase locked loop ultrasonic interferometer with the nominal frequency of the ultrasonic waves being 2.25 MHz.
Document ID
19900037594
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Prosser, W. H.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 14, 2013
Publication Date
March 1, 1990
Publication Information
Publication: Journal of Reinforced Plastics and Composites
Volume: 9
ISSN: 0731-6844
Subject Category
Composite Materials
Accession Number
90A24649
Distribution Limits
Public
Copyright
Other

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