Experiments were conducted to determine the effects of damage growth caused by humidity cycling between 95% RH and 0% RH at 40°C on AS4/3502 graphite/ epoxy composite material. Tests were performed to measure tensile and compressive moduli, Poisson's ratios, and ultimate strengths. Fracture behavior was determined from double cantilever beam tests in which energy release rates were measured. In virtually all cases it was found that the cycling conditions utilized in this work did not lead to any sig nificant changes in moduli, Poisson's ratio, ultimate strength, or energy release rates de spite the fact that micro-level damage was known to be present.
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