Development of a Constitutive Theory for Short Fiber Yams

This article deals with the effects of fiber orientation and bending deformation on staple yarn behavior. First, the effect of fiber orientation is shown by comparing yarn properties determined using three different fiber orientation cases. Then, for a given fiber orientation distribution, radial distributions of both tensile stress and lateral pressure along the yarn cross section are predicted. The fiber obliquity effect at high yarn twist levels is attributed more to fiber bending deformation. Finally a modified yarn model is proposed that produces predictions in close agreement with existing experimental results.