Fatigue behavior of short carbon fiber reinforced epoxy composites

This paper intends to contribute to a better understanding of the failure mechanisms on short fibers composites with high fiber volume fractions, for which relatively low values of stiffness and resistance efficiency are reached. For the aforementioned purpose, the current work used composite plates that were manufactured by compression molding and incorporating short carbon fibers reinforcements (0.5 mm in length with 5-20% volume fiber fraction) into an epoxy resin. For low volume fractions, the composites exhibit static mechanical properties nearly proportional with fiber content. However, for high volume fraction lower efficiency was observed for both tensile stiffness and strength. As expected, the strain at failure decreases with the increasing of the fiber content. Fatigue strength follows a similar behavior of static strength, increasing until the fiber content is of 17.5% in volume, but afterwards remains nearly constant. Fatigue life is mainly influenced by fiber dispersion and porosity.