The fracture mechanisms of three kinds of model composities, such as the unidirectional glass fiber, the 0°/90° glass fiber and the plain weave cloth reinforced composites, were studied by using the acoustic emission (AE) method in tension, and by observation with optical and electron microscopes.
It was found that the fracture mechanisms were different from each other because of their different types of reinforcement, and the AE event rate and the AE total energy were the effective parameters to make them clear. The fracture mechanisms could not be explained by the AE amplitude distribution, but by the power spectrum of AE waves based on the frequency analysis. The dominant frequencies in AE signals due to the matrix cracking, the debonding, the fiber breaking and the friction between fibers could be specified, and they increased in order of such phenomena.