Abstract
Delamination fatigue crack propagation behavior was investigated for four kinds of CF/epoxy laminates (Toray T300/#3601, T800/#3601, T300/#3631, and T800/#3631). Tests were carried out under mode I opening loading by using double cantilever beam specimens. The effect of reinforcing fiber on the delamination fatigue crack growth behavior was very small. The fatigue crack growth behavior was mainly controlled by matrix resin. The analysis of the equivalent stress intensity range proposed by the present authors indicated that the contribution of maximum load was large in delamination fatigue crack propagation of the laminates tested here. The degree of the contribution of maximum load was higher for more brittle resin. The improvement of the interlaminar fracture toughness was not fully transferred to the improvement of threshold value of the fatigue crack growth. The mechanism of delamination fatigue crack propagation agreed well with the fractographic observation.
