The effects of cyclic moisture aging on a glass/vinyl ester composite system

As composite materials find increasing use in infrastructure applications where the design lives are typically much longer than aerospace applications, the issue of durability becomes more critical for these materials. The tolerance of composites to damage by cyclic loading and moisture ingression is of utmost importance. This study addresses the change in quasi-static and R = 0.1 (tension-tension) fatigue behavior of a commercial glass/vinyl ester system due to moisture. Quasi-static tensile strength is reduced by 24% at a moisture concentration of 0.95%, by weight. This reduction in strength is not recovered when the material is desorbed, suggesting that the exposure to moisture caused permanent damage in the material system. The fatigue performance of unaged, or “As Delivered”, and saturated material is similar, but cyclical moisture ingression alters the fatigue performance of the composite system tested. This study highlights the effect of short term cyclic moisture aging and the effects on strength and fatigue performance of a glass/vinyl ester pultruded composite system.