SYMPOSIA PAPER Published: 01 January 1990

Surface Crack Analysis Applied to Impact Damage in a Thick Graphite/Epoxy Composite


The residual tensile strength of a thick graphite/epoxy composite with impact damage was predicted using surface crack analysis. The damage was localized to a region directly beneath the impact site and extended only part way through the laminate. The damaged region contained broken fibers, and the locus of breaks in each layer resembled a crack that was nearly perpendicular to the direction of the fibers. In some cases, the impacts broke fibers without making a visible crater. The damage was represented as a semielliptical surface crack of the same width and depth as the cross section of the damage. The maximum length and depth of the damage were predicted using the Theory of Elasticity and a maximum shear stress criterion. The predictions and measurements of strength were in good agreement.

Author Information

Poe, CC
NASA Langley Research Center, Hampton, VA
Harris, CE
NASA Langley Research Center, Hampton, VA
Morris, DH
Virginia Polytechnic Institute and State University, Blacksburg, VA
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Developed by Committee: E08
Pages: 194–212
DOI: 10.1520/STP23435S
ISBN-EB: 978-0-8031-5121-5
ISBN-13: 978-0-8031-1284-1