http://worldcat.org/entity/work/id/137513833

Hygrothermal Influence on Delamination Behavior of Graphite/Epoxy Laminates

The hygrothermal effect on the fracture behavior of graphite/epoxy laminates has been investigated as part of an overall effort to develop a methodology for damage-tolerance predictions in advanced composite materials. Several T3OO/934 laminates were tested using a number of specimen configurations (double cantilever, compact tension, and cracked lap shear) in order to evaluate the effects of temperature and humidity on delamination fracture toughness under Mode I and Mode II loading. The specimens were exposed to different humidity levels and temperatures for varying periods of time prior to testing. The pre-exposed specimens were tested under room conditions, and fracture energies during initiation and propagation were estimated. Acoustic emission was used to detect crack initiation. It was indicated that moisture has a slightly beneficial influence on fracture toughness or critical strain energy release rate during Mode I delamination, but has a slightly deleterious effect on Mode II delamination and Mode I transverse cracking. The failed specimens were examined by SEM and topographical differences due to fracture modes were identified. The effect of moisture on fracture topography could not be distinguished. (AN).

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