Fracture Mechanism and Acoustic Emission of Unidirectional Flawed Materials with Carbon Fiber Reinforced Nylon 6

Abstract

The fracture behavior during tensile tests on unidirectional flawed samples of carbon-reinforced nylon 6 at angles of 0°, 45° and 90° between fiber and loading direction has been studied with simultaneous AE monitoring. It was observed that the direction of crack propagation was along fiber/matrix interface in each case of 0°, 45° and 90° samples. For on-axis loading, the fracture energy was large, the crack propagated rapidly, and the fracture surface was smooth, while for off-axis loading these were contrary. Furthermore, the fiber/matrix debonding, which is the main failure mode in unidirectional materials, has been investigated in detail from the results of AE parameters, crack propagating behavior and SEM observation. An obvious difference was found in AE amplitude as well as in the distribution of power spectra between on-axis and off-axis loadings.