Fatigue behaviour of carbon fibre/PEEK laminate composites

The fatigue behaviour of continuous carbon fibre-reinforced poly(ether ether ketone) (PEEK) composites under tension-tension (T-T) and tension-compression (T-C) loadings was investigated. A quasi-isotropic lay-up was used, namely [0/45/90/-45]_2s AS-4/PEEK. The experimental results for fatigue life and residual tensile strength under different stress amplitudes are analysed by the median rank method. The influences of stress amplitude on the fatigue life and the residual tensile strength were investigated. The S-N curve is presented by the pooled Weibull distribution function. Two segments of the S-N curves show a different failure mode in the fatigue failure of the thermoplastic composites. Moreover, a residual strength degradation model is used to predict the residual strength for the composites subjected to a number of fatigue cycles and to simulate the effects of the stress amplitude on the fatigue life. According to the obtained results, the correlation between the experimental data and the theoretical prediction is in good agreement.