Static and Fatigue Tensile Properties of Cross-Ply Carbon-Fiber-Reinforced Epoxy-Matrix-Composite Laminates with Thin Plies

Carbon-fiber-reinforced epoxy-matrix composite (CFRP) laminates with thin plies have strong damage-resistance properties compared with standard prepregs. The static and fatigue tensile fracture behavior of cross-ply CFRP laminates with thin plies should be further studied to establish the applicability of thin-ply prepregs for industrial structures. In this study, the static and fatigue tensile properties of cross-ply, high-strength polyacrylonitrile (PAN)-based carbon-fiber (T800SC)-reinforced epoxy-matrix composites with thin plies were investigated. The fiber orientations of the CFRP specimens were set to cross-ply with [0/90](10S) (subscript S means symmetry), [(0)(5)/(90)(5)](2S), and [(0)(10)/(90)(10)](S). The static and fatigue tensile characteristics of the cross-ply CFRPs with thick plies with [0/90](2S) and [(0)(2)/(90)(2)](S) were also investigated for comparison. Under static loading, the tensile strength and failure strain of the thinnest 90 degrees-ply-CFRP specimens were more than 5% higher than those of the other 90 degrees-ply-thickness specimens. However, the tensile moduli and Poisson's ratios were comparable between the cross-ply CFRPs with thin and thick plies. Under fatigue loading, the fatigue responses of the thinnest 90 degrees-ply-CFRP specimens were 3% higher than those of the other 90 degrees-ply-thickness specimens during lower-fatigue-cycle testing (<10(5) cycles). However, during higher-fatigue-cycle testing (>10(5) cycles), the fatigue responses decreased, with a decrease in the 90 degrees-ply thickness, and the fatigue characteristics of the thinnest 90 degrees-ply-CFRP specimen were 7% lower than those of the other cross-ply thin- and thick-ply-CFRP specimens.