A MICROSTRUCTURAL APPROACH TO THE EFFECTIVE TRANSPORT-PROPERTIES OF MULTIPHASE COMPOSITES

A group of physical properties, such as electrical conductivity, diele ctric constant, magnetic permeability thermal conductivity and diffusi on coefficient, are governed by the same form of constitutive equation s and are therefore mathematically analogous. This group of physical p roperties of composite materials, usually referred to as the effective transport properties in the literature, is highly dependent upon the statistical arrangement of their constituent phases. Consequently, a s uccessful theoretical solution to the correlation between the effectiv e transport property and the microstructure has to address the statist ics of microstructural feature. In this paper a new microstructural ap proach has been developed for predicting the effective transport prope rties of multiphase composites. In contrast with the existing models, the present approach can consider not only the effect of volume fracti on but also the effects of particle shape and phase distribution. It h as been applied to various two-phase and multiphase composites includi ng porous materials. The theoretical predictions are in good agreement with the experimental data drawn from the literature. It has been sho wn that the present approach is superior to the various bounds in term s of the accuracy of prediction and the range of applicability. Finall y, the effect of phase contiguity on the effective transport propertie s of two-phase composites has also been discussed. It is found that th e effective transport properties increase with increasing phase contig uity in a given composite system.