Measurement of fiber orientation in short-fiber composites

Abstract The degree of fiber orientation in short-fiber composites plays an important role in determining many properties of these materials. In order to predict the toughening of a composite by using fiber reinforcements, we must consider the orientation of fibers as described probabilistically by the distribution function f(ψ), where ψ is the angle which each fiber makes with the normal to the crack face. Here, a method for the characterization of the fiber orientation is built up in successive steps. In a first step the measurements of a planar array of fibers is afforded by extracting the important statistical information contained in a calculated Fraunhofer diffraction pattern of the fiber distribution. Subsequently, a method is proposed allowing us to derive the relevant f(ψ) distribution from the two-dimensional characterization of two orthogonal plane sections of the composite.