SEDL / STP / STP696-EB / STP36034S

Moisture-Induced Surface Damage in T300/5208 Graphite/Epoxy Laminates

Shirrell, CD
senior research engineer, General Motors Research Laboratories, General Motors Technical Center, Warren, Mich

Leisler, WH
Engineering technician and aerospace engineer, Air Force Flight Dynamics Laboratory, Wright-Patterson Air Force Base, Ohio

Sandow, FA
Engineering technician and aerospace engineer, Air Force Flight Dynamics Laboratory, Wright-Patterson Air Force Base, Ohio

Pages: 14    Published: Dec 1979

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Abstract

A microscopic examination of hygrothermally expsoed T300/5208 cross-ply laminates is described. Moisture-induced surface and edge microcracks were observed in specimens exposed at 82° and 9, 20, 37, 74, and 91 percent relative humidity or water immersion. Specimens exposed at similar relative humidities but at lower temperatures (21, 43, and 63°C) generally did not form microcracks.

The severity and frequency of the microcracking at 82°C increased with relative humidity. The majority of the microcracks were observed to be oriented parallel to the graphite fibers in the surface laminae. Specimens with extensive microcracks were also observed to exhibit non-Fickian diffusion phenomena during their hygrothermal exposure.