Effect of void on the interlaminar shear fatigue of carbon fiber/epoxy composite laminates

The effect of void content on the static interlaminar shear strength and interlaminar shear fatigue properties of carbon fiber reinforced epoxy ［(±45)/0₄/(0, 90)/0₂］_Scomposite laminates was studied. The laminates with void volume fraction 0.4% ~ 6.6% were prepared by applying different autoclave pressure. The void content and microstructure characteristics of voids were studied using optical image analysis. The results show that the fraction of large voids(S>7.85×10-3mm²) and mean void content increase with the decreasing autoclave pressure. Each 1% increase in void content with the void volume fraction in the range 0.4% ~ 4.6% induces a 2.4% reduction in interlaminar shear strength. The interlaminar shear fatigue life decreases with the increasing void content. The effect of voids on fatigue is more significant than on static failure. Large voids promote the initiation and propagation of cracks.