Using FRP prepared from low density polyethylene and carbon fibers, the relation between its deformation and the variation of short fiber orientation, during stretch, creep and stress relaxation, is studied by comparison between observed and calculated data which are obtained on the assumption that the deformation of FRP occurs uniformly and that the fibers are rigid. On the basis of this result, the variation of short fiber orientation distributions and their standard deviations are

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... Good agreement is obtained between observed and calculated curves. The variation of short fiber orientation during stretch and creep is represented by elongation, shrinkage, and initial orientation angle, regardless of the fiber length and the position. If short fibers adhere to matrix sufficiently tight, the variation of short fiber orientation is reversible regardless of the deformation process during creep, but not observed during stress relaxation. As the deformation of FRP increases, calculation shows that probability density curves of the fiber orientation distributions become sharp and that their standard deviations gradually decrease. 80 Journal of The Textile Machinery Socie ty of Japan