Hygroscopic effects on the penetration-resistance behavior of a specially-orthotropic CFRP composite plates

This paper addresses the impact responses of dry and wet specially-orthotropic cross-ply CFRP composite plates under low-velocity impact loading. Experimental tests were performed for five different moisture content conditions using anti-symmetric cross-ply composite plates. To analyze the hygroscopic effects, all plates were immersed in hot water for water absorption and then impacted by constant weight via an impactor. Absorbed water cause matrix swelling and leads to disbanding between the matrix and fiber at the interface, as observed in SEM images. The results showed that plates with a higher level of moisture content showed more undulation in the time-force curve and a relatively small change in the peak force for all plates. Moisture content does not have a substantial effect on the penetration-resistance of the plates. The flexural rigidity or stiffness of the plates decreases due to moisture content and large damage sizes were observed for wet specimens in the C-scan pictures as compared to dry plate.