Effective Thermal Conductivities of Fibrous Composites

Abstract

Most composite research to date has been concerned with mechanical properties. However, with anticipated use of composite materials in high temperature aero-space structures and other applications, thermal properties have become essential design information. This paper summarizes the results of a rigorous analysis to determine the steady-state effective thermal conductivities of fiber-matrix type of composites. A principal purpose of the present work is to investigate a class of heat conduction problems for which the proximity effects of the embedded fibers are significant. The fibers are considered dispersed uniformly in a matrix of resin. The dispersion patterns or configurations considered are: (1) uni-directional fibers in a matrix, as the simplest geometry, and (2) 0/90 configuration in which uni-directional tapes are overlaid at 90 deg to each other. The method of analysis is to solve a two-region steady-state heat conduction equation analytically or numerically. The analysis assumes prior knowledge of the geometry and the thermal conductivities of the composite constituents.