| Accurate prediction of the effective thermal conductivity of composite materials is critical in composite technology. A majority of the existing analytical models to predict the effective thermal conductivity are applicable only for composites consisting of isotropic fibers and matrices, perfect fiber-matrix adhesion, and composites free of porosities. Unfortunately, this is not the case for a majority of engineering applications using composite materials. The models that propose bounds for the effective thermal conductivity predict results that are extremely widespread and, consequently, demonstrate limited success. Furthermore, these analytical models are seldom validated by experimentally determined data.; The present model for the transverse effective thermal conductivity of fibrous composites, apart from accounting for the matrix and fiber thermal conductivity, fiber volume fraction, and fiber radius, also considers a finite fiber-matrix thermal conductance value, orthotropic fibers, and composite porosity. The model is not limited to any particular class of composites and may be used to predict the transverse effective thermal conductivity of organic, metallic, and ceramic composites. The factors that critically influence the predicted data are the matrix thermal conductivity, fiber-matrix interfacial conductance, and the fiber volume fraction.; The model is compared to present experimentally determined transverse effective thermal conductivity of composites consisting of different graphite fibers and varying fiber volume fractions in an organic matrix. The model is also compared with published experimental data for metal, organic, and ceramic matrix composites. It is demonstrated that the data predicted by the model compares well with experimentally obtained values.; In order to examine the fiber-matrix interface, fiber volume fraction, fiber radius, and porosities within the composite, a scanning electron microscopy study was undertaken. This study revealed valuable information that helped explain the results obtained. |
