Fiber orientation in FRP is generally caused by a manufacturing process. The mechanical and electrical properties of FRP depend upon the degree of orientation of fibers so that it is important to evaluate the orientation of fibers accurately.
Fundamental items for evaluating the fiber orientation in FRP are reported in this paper. Our previous studies on a two-dimensionally distributed straight fiber model have revealed that the orientation of straight fibers can be obtained by the corresponding Fraunhofer diffraction patterns. It is interesting to determine the distribution of orientation through the intensity of Fraunhofer diffraction pattern.
The distribution of fiber orientation for straight fibers model is quantitatively determined by comparing the experimental with theoretical intensity curves of Fraunhofer diffraction patterns. If the fiber orientation for straight fibers model has normal distribution, its standard deviation and mean value are determined. In the case of uniform distribution, the width of the distribution is obtained. This result suggests that the Fraunhofer diffraction method can be used for a quantitative evaluation of the orientation distribution for fibers in FRP.
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