Two-stage fatigue loading of woven carbon fibre reinforced laminates

A brief review of the models used to predict the cumulative fatigue damage in FRP composites is presented. Two-stage fatigue loading of a [0/90,+/- 45(2),0/90](s) quasi-isotropic woven carbon fibre/epoxy resin laminate was evaluated at stress ratio R=0.05 and the failure mechanisms investigated using x-radiography after each loading stage. The results are presented in terms of fatigue strength and damage growth and are compared with those in the literature. A low-to-high loading sequence is more damaging than a high-to-low one and the Palmgren-Miner linear damage rule may no longer be valid for this kind of material, as previously reported.