Fatigue crack propagation in short-carbon-fiber reinforced plastics evaluated based on anisotropic fracture mechanics

The influence of fiber orientation on crack propagation was studied with single edge-notched specimens cut from injection-molded plates of fiber-reinforced polyphenylene sulfide (PPS). Fracture mechanics parameters were calculated by FEM based on anisotropic elasticity. For mode I crack propagation in specimens parallel (MD) and perpendicular (TD) to molding direction, difference in crack propagation rate, dc/dN, among specimens becomes small when correlated to a crack-tip-opening radius parameter, HIΔGI, where HI is a compliance parameter. Including crack propagation under mixed loading, all the data tend to merge a single relation when correlated to total energy-release-rate range divided by Young's modulus, ΔGtotal/Eθ.