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Analysis of matrix cracking and local delamination in (0/theta/-theta)s graphite epoxy laminates under tensile loadThree-dimensional element analyses of (0/theta/-theta)s graphite epoxy laminates, where theta = 15, 20, 25, 30, and 45 deg, subjected to axial tensile load, were performed. The interlaminar stresses in the theta/-theta interface were calculated with and without a matrix crack in the central -theta plies. The interlaminar normal stress changes from a small compressive stress when no matrix crack is present to a high tensile stress at the intersection of the matrix crack and the free edge. The analysis of local delamination from the -theta matrix crack indicates a high strain energy release rate and a localized Mode I component near the free edge, within one-ply distance from the matrix crack. To examine the stress state causing the matrix cracking, the maximum principal normal stress in a plane perpendicular to the fiber direction in the -theta ply was calculated in an uncracked laminate. The corresponding shear stress parallel to the fiber was also calculated. The principal normal stress at the laminate edge increased through the ply thickness and reached a very high tensile value at the theta/-theta interface indicating that the crack in the -theta ply may initiate at the theta/-theta interface.
Document ID
19930065236
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Salpekar, S. A.
(Analytical Services and Materials, Inc. Hampton, VA, United States)
O'Brien, T. K.
(U.S. Army, Vehicle Structures Directorate; NASA, Langley Research Center Hampton, VA, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Journal of Composites Technology & Research
Volume: 15
Issue: 2
ISSN: 0885-6804
Subject Category
Composite Materials
Accession Number
93A49233
Distribution Limits
Public
Copyright
Other

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