The effect that a closure approximation has on material property predictions has received little attention in the literature. Accordingly, this research demonstrates that current objective fourth-order closures are limited by their assumed orthotropic form, whereas existing sixth-order closures are shown to provide a material representation with fewer symmetries than orthotropic. Of particular interest here is the computation of the various components of the stiffness (or compliance) tensor.

Numerical calculations demonstrate the existence of shear-extensional and shear-shear coupling in simple homogeneous flows and in the non-homogeneous flow found in a center-gated disk as shown here. Although these components are small in comparison to principal components of the compliance tensor, they are ignored by all orthotropic fourth-order closures (see e.g., ORT results given here). However, these terms can be computed with the sixth-order INV6 closure. Material tensor components are computed here from the fourth-order orientation tensor, and matrix and fiber properties using method given by Advani and Tucker [1987].

The Effect of Fiber Orientation Closure Approximations on Mechanical Property Predictions. D.A. Jack and D.E. Smith. Manuscript accepted for publication in Composites, Part A, 2006.

Mechanical Properties From the INV6 Closure for Short-Fiber Suspensions. D.A. Jack and D.E. Smith. ANTEC 2006 -- Proceedings of the 64th Annual Technical Conference and Exhibition, Charlotte, N.C., May, 2006.

• U.S. National Science Foundation
• U.S. Department of Education