Moisture Diffusivity of Unidirectional Composites

Abstract

The moisture diffusion in unidirectional fiber-reinforced composite materials is formulated in terms of relative moisture concentration which cor responds to the temperature for the heat conduction problem. And the effec tive transverse moisture diffusivity of the composite materials with random array packing of fibers is predicted based on the properties of the constituent matrix and fibers by establishing a random array model. It is found that if the degree of randomness increases, the transverse diffusivity decreases remarkably. The theoretical prediction is in good agreement with the ex perimental data obtained by the authors and other researchers. And the analogy between the moisture diffusion and the thermal conduction or the longitudinal shear loading is discussed, pointing out some error in similarity used to predict the moisture diffusivity of composite materials in the literature.