In order to evaluate the change in the mechanical properties, mass and coeffcient of thermal expansion of composites under ground and space environment, graphite/epoxy composite specimens were exposed to simulated ground environmental conditions including temperature, moisture, ultraviolet radiation and low earth orbit environmental conditions including ultraviolet radiation, thermal cycling and high vacuum. The failure time of composite structure exposed to the attack of ground and low earth orbit environmental factors was predicted by using four modified failure criteria. Modified failure criteria were expressed as a function of stress as well aging time. Also, transient analyses were conducted to predict the thermal distortion of an orbiting solar array incuding degardation effects of composite materials.
