The effect of frequency on tension-tension fatigue behavior of unidirectional and woven fabric graphite-epoxy composites

In this paper, the effect of different values of load frequency on the evolution of the stress versus number of cycles to failure curve for a graphite-epoxy composite is studied. Two types of materials have been considered: unidirectional tape and woven fabric laminates. Fatigue tension-tension tests at different orientation angles and several frequency values have been carried out. The results show there is almost no effect of the load frequency in the S-N curve of unidirectional laminates. For woven fabric laminates, only under off-axis tension, the effect of frequency becomes a remarkable parameter in the fatigue behavior.