開口変位分布に基づく短繊維CFRPの疲労き裂進展挙動に及ぼす板厚の影響

抄録

The influence of plate thickness on the crack propagation behavior was studied by using center-notched specimens which were cut from injection-molded plates (IMP) of short carbon-fiber reinforced polyphenylene sulfide(PPS) at two fiber angles relative to the molding flow direction (MFD), i. e. θ=0° (MD), 90°(TD). The thickness of IMP was 1, 2 and 3mm. IMP have three layer laminated structure where the fiber orientation in the shell layer was parallel to MFD and that of the core layer was nearly perpendicular to MFD. The fraction of the shell layer decreases with decreasing plate thickness. The macroscopic crack propagation path was perpendicular to the loading axis in MD and TD, showing mode I propagation. In the relation between crack propagation rate, da/dN, and stress intensity factor, ΔK, da/dN increases with increase in thickness for MD. Conversely, da/dN decreases with increase in thickness for TD. Crack opening displacement obtained by DIC (Digital Image Correlation) method is smaller than that analyzed by FEM in 1mm IMP.