Interphase Influence on the Effective Thermal Conductivity Coefficients of Fiber Composites

This study proposes a two-scale approach to determining the effective thermal conductivity of fibrous composite materials. The analysis was first carried out at the fiber-interphase level to calculate the effective thermal conductivity of this system, and next at the whole composite structure level. At both scales, the system behavior was analyzed using the finite element method. To determine the effective thermal conductivity for the fiber-interphase system, an inverse problem was solved, while a simple unidirectional heat conduction test was performed for the entire composite. The simulations were carried out for typical fibrous composites: carbon fibers-epoxy resin and glass fibers-epoxy resin. The results showed a significant impact of realistically observed interphase thicknesses on the heat conduction properties of the tested composites.