The elastic modulus of misaligned short-fiber-reinforced polymers

The elastic modulus of misaligned short-fibre-reinforced polymers depends critically on the fiber length distribution and the fiber orientation distribution in the final composite product. In this paper the fibre orientation and length distributions are modelled by suitable probability density functions. The laminate analogy approach is used to predict the elastic modulus of short fibre-reinforced polymers by considering the effects of the fibre length and orientation distributions. The laminate analogy approach,vas used previously only for the case of a planar fibre orientation distribution, whereas this approach is extended in this study to any general case of a three-dimensional spatial fibre orientation distribution. It is of particular interest to note that the composite elastic modulus depends not only on the mean fiber length and the mean fiber orientation angle but also on the modal value of fiber length, the modal fiber orientation angle, the fiber orientation coefficient and the cumulative fiber orientation distribution. The laminate analogy approach is compared with other theories and its advantages over other theories are displayed. Comparison is also made with existing experimental results and the agreement is found to be satisfactory. (C) 1998 Elsevier Science Ltd. All rights reserved.