Fatigue life of unidirectional 90° carbon/epoxy laminates made of conventional and ultra-thin plies varying manufacturing and testing conditions

Abstract

Unidirectional 90° laminates (UD-90) have been tested under tension–tension loading (R = 0.1) to comprehend the effect of different conditions on their fatigue life. Four different case studies have been evaluated: the existence of porosity using two different UD-90 laminates cured at different pressures in an autoclave, the importance of the surface finishing when a pressure plate is used, the effect of load frequency, and the relevance of the prepreg thickness comparing 190 and 50 g/m2 prepregs while keeping the total thickness of the laminates constant. All these case studies have been analyzed employing S–N curves as the starting point of the authors' current research for the prediction of the onset of transverse damages in ultra-thin plies in the assessment of different cross-ply laminates under cyclic loading.