Abstract
This paper presents characteristics of fatigue in quasi-isotropic graphite/epoxy laminates, [45/0/45/90] s. Tension-tension fatigue loading with the stress ratio R=0.1,was applied to get the S-N diagram. During the fatigue tests, the cumulative damage evolution was photographed microscopically certain fatigue stages to make clear the fatigue mechanism. It was found that S-N diagram was linear in the range of this study. For the progression of the transverse crack and the delamination, it was found that the transverse cracks in the 90deg layer were saturated at an early stage, but that those in the 45deg and the-45deg layer and the delamination in the all layers were increased gradually. It was suggested that the delamination between the 45deg and the 0deg layers plays a important role for applying the Palmgren-Miner's rule for this laminates in this paper.
