Durability of a graphite/epoxy woven composite under combined hygrothermalconditions

The objective of this effort was to evaluate and model the effects of moist ure, temperature and combined hygrothermal conditions on the strength and l ife of a graphite/epoxy woven composite material system. The material syste m specified is a candidate for use in an advanced subsonic aircraft engine, and the imposed environmental conditions were considered to be representat ive of engine service conditions. Fatigue and residual strength data showed that initial and residual tensile properties and fatigue life of the mater ial were only minimally affected by any of the imposed environmental condit ions for the fatigue stress levels considered in this study. Based on this data, it was shown a residual-strength-based life prediction approach could be used to model strength and life with reasonable results. Fatigue damage progression and accumulation were found to be dependent on testing environ ment, suggesting that more adverse effects of environment on strength and l ife may be manifested for other types of loading (i.e., off-axis loading). (C) 2000 Elsevier Science Ltd. All rights reserved.