Fatigue Behavior of Glass-Reinforced Epoxy Resin Submitted to Hot-Wet Aging

To assess the effect of hot-wet aging on the properties of a glass-reinforced epoxy resin, three kinds of specimens were subjected to static and dynamic (fatigue) tests, in both dry and moisture-saturated conditions. Although a reduction of both elastic properties and strengths was found, it seems that hygrothermal aging has no effect on the S-N fatigue behavior when the part at low loads is considered. It is proposed that there is a balance between the damage generated by micro-effects (such as fiber damaging, resin micro-cracking or micro-crazing) and the increased energy dissipation capability of the resin generated by the absorbed moisture. The first kind of behavior is dominant at high loads (low number of cycles: i.e., the static situation), while the second is more important where a high number of cycles is concerned.