Solving Heat Dissipation Problems in Unidirectional Composite Structure

Abstract

Due to their poor thermal conductivity, plastic based composites could have high local temperatures when heated. The rigidity of the material could then decrease dramatically leading to a premature failure when it's loaded. In order to avoid such problem, heat dissipation is necessary. When heat transfer by cooling becomes difficult, conductive material fillers could be added to the raw material, providing that they would not reduce its strength. Metallic fillers are used in the industry under various forms depending on the manufacturing process.

This paper presents the results of a finite element analysis of the heat dissipation capacity of a unidirectional GFRE in which highly heat conductive carbon fibers are added. The study shows the effect of the thermal conductivity, the amount and the dispersion of such fillers on the temperature decrease in the composite submitted to a concentrated transient heat source. An increase of the filler conductivity has a significant effect on the temperature drop at the neutral axis of the unidirectional composite. However, when the filler conductivity is high, a "breakover" point beyond which continued increase in the filler thermal conductivity has small benefits. In this paper, it is shown that the replacement of a small amount of glass fibers by carbon fibers, leads to an important decrease in the temperature in the composite. A continued increase in the volume fraction of the conductive material, has little effect on the temperature decrease. The study also shows that the distribution of the conductive fibers in the composite cross-section has an important effect on its thermal efficiency.