Prediction of failure thermal cycles in graphite/epoxy composite materialsunder simulated low earth orbit environments

In order to evaluate the changes in the mechanical properties, mass and coe fficient of thermal expansion of composites in space, graphite/epoxy compos ite specimens were exposed to simulated low earth orbit (LEO) environmental conditions including ultraviolet radiation, thermal cycling and high vacuu m. Surface morphology was investigated by using a scanning electron microsc ope, and outgassed products were analyzed with a quadrupole mass spectromet er. The failure cycle of composite laminates exposed to the attack of LEO envir onmental factors was predicted by using four modified failure criteria. The modified failure criteria were expressed as a function of stresses as well as thermal cycles. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.