SYMPOSIA PAPER Published: 01 January 1997

Hygrothermal Influence on the Free-Edge Delamination of Composites Under Compressive Loading


This paper reports on determination of the individual and combined effects of temperature and moisture on the initiation of free-edge delamination in a [903/303/-303]s graphite/epoxy laminate. Dry and wet specimens were tested at various temperatures under uniaxial compression. The onset of delamination was determined by monitoring axial and transverse strains and confirmed by microscopic examination of the polished specimen edges. Interlaminar free-edge stresses were analyzed using a global-local model, and the elastic constants for these calculations were determined experimentally for the various hygrothermal conditions. The results of this stress analysis were applied to predict the onset of delamination in conjunction with the maximum effective stress criterion. Delamination in all cases occurred at the interfaces predicted, and the predicted stress for the onset of delamination compared reasonably well with experiments. While the curing residual stresses decrease with increasing moisture content and test temperature, so does the interlaminar tensile strength, and these two effects compete in their influence on the stress for the initiation of delamination.

Author Information

Crasto, AS
University of Dayton Research Institute, Dayton, OH
Kim, RY
University of Dayton Research Institute, Dayton, OH
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Developed by Committee: D30
Pages: 381–393
DOI: 10.1520/STP19938S
ISBN-EB: 978-0-8031-5353-0
ISBN-13: 978-0-8031-2411-0