Effects of moisture absorption on damage progression and strength of unidirectional and cross-ply fiberglass–epoxy composites

摘要

Fiber-reinforced-polymer composites (FRPs) possess superior mechanicalproperties and formability, making them a desirable material for constructionof large optimized mechanical structures, such as aircraft, wind turbines,and marine hydrokinetic (MHK) devices. However, exposure to harsh marineenvironments can result in moisture absorption into the microstructure of theFRPs comprising these structures and often degrading mechanical properties.Specifically, laminate static and fatigue strengths are often significantlyreduced, which must be considered in design of FRP structures in marineenvironments. A study of fiberglass epoxy unidirectional and cross-plylaminates was conducted to investigate hygrothermal effects on the mechanicalbehavior of a common material system used in wind applications. Severallaminates were aged in 50 °C distilled water until maximumsaturation was reached. Unconditioned control and the saturated samples weretested in quasi-static tension with the accompaniment of acoustic emission(AE) monitoring. Cross-ply laminates experienced a 54 % reduction instrength due to moisture absorption, while unidirectional laminatestrengths were reduced by 40 %. Stress–strain curves and AE activity ofthe samples were analyzed to identify changes in damage progression due toaging.