Predicting the Orientation of Short Fibers in Thin Compression Moldings

A method is presented for predicting the distribution of orientation of rigid short fibers in thin compression molded parts. The method extends Folgar and Tucker's model for fiber orientation in a concentrated suspension to the case of spatially non-uniform flows and orientation states. A generalized Hele-Shaw model is used to predict flow and defor mation during mold filling. Other assumptions are appropriate for sheet molding com pound : fibers much longer than the part thickness and a cold material molded in a hot mold. The predictions compare favorably to experiments on sheet molding compound and on a model suspension of nylon monofilaments in silicone oil.