Prediction of the thermal conductivities of four-axial non-woven composites

A numerical model for the effective thermal conductivities of multiaxial non-woven composites (NWCs) was derived by using the definition of thermal resistance. The model uses the analogy between the diffusion of heat and electrical charge. A four-axial NWC was fabricated and its thermal conductivity was measured in order to verify the prediction model. The thermal conductivity of a four-axial NWC predicted from the proposed equation was compared with thermal conductivities measured and calculated from an existing volume average method which employs a micromechanical theory and conventional tensor transformation rules to obtain the effective property for the unit cell of NWCs. The comparison showed that thermal conductivities by the proposed equation are in good agreement with those by the volume averaging method and the experimental data. In addition, the dependence of effective thermal conductivities of NWCs on the transverse thermal conductivity of rods was investigated.