Orientation Behavior of Fibers in Concentrated Suspensions

A mathematical model is developed to predict the orientation distribution function of rigid fibers in concentrated suspensions. The model contains a phenomenological term to account for interactions between fibers. Predictions of the model are tested against experiments in simple shear flow, using suspensions of nylon monofilaments in silicone oil. The results compare favorably for steady-state distributions, though the theory predicts a more rapid approach to steady state than actually occurs. The model predicts, and experiments show, that fiber orientation is not reversible when the flow is reversed. The model is useful for predicting the effects of processing on fiber orienta tion in short fiber composites.