Effect of Fillers and Voids on Compressive Yield of Epoxy Composites

Abstract

Two series of epoxy composites, filled and porous, were loaded in compression up to yield under several constant strain rates. Results indicate a linear relationship between yield stress and log strain rate, characterized by a constant slope for the different com positions, and almost linear dependence of yield stress on filler content. A simplified empirical formula was derived for the yield stress of filled composites as function of filler content and strain rate. Similar dependence was found for porous composites. The strain-rate dependence indicates non-Newtonian visco plastic behaviour obeying the corresponding Eyring equation. The filler content was found to have almost no effect on the activation volume terms, and its main effect is apparently with regard to the activation energy characteristics of the yielding process.