Strength and Reliability of Unidirectional CFRPs with Different Fiber Surface Properties
Yoshikazu MIWA, Munenori KASEBE, Koichi GODA, Junji OHGI, Satoshi NAGATSUKA and Hitoshi KODAMA
Abstract:Four kinds of fiber surface properties were created by electrolytic oxidation on continuous carbon fibers with uneven and smooth surfaces, in order to clarify the effect of bond strength between the fiber and matrix on the mechanical properties of unidirectional carbon fiber reinforced plastics (CFRP). It was proved from a fiber fragmentation test, using single fiber composites embedded in epoxy, that interfacial shear strength (IFSS) increases with an increase in ratio of oxygen to carbon (O/C) on the fiber surface. The result of the tensile tests of CFRP specimens with the different fiber surface properties showed that appropriate IFSS or O/C not only increases tensile strength, but decreases coefficient of variation in tensile strength. It was discussed from the previously reported simulation results that such an optimal IFSS or O/C should be given by an only value. Furthermore, using the same CFRP specimens, relation between IFSS and fatigue life was experimentally investigated. Key Words:CFRP, Carbon fiber, Epoxy, Single fiber composite, Electrolytic oxidation, Interfacial shear strength, Tensile strength, Fatigue life, Weibull modulus