Fatigue behaviour of CF/PEEK composite laminates made from commingled prepreg .1. Experimental studies

The static and fatigue properties of continuous AS4 carbon fibre reinforced polyetheretherketone (PEEK) composite laminates made from commingled unifabric prepreg were investigated under static tension and tension-tension fatigue loading. Three different lay-ups were studied, namely [0](16), [90](16) and [0(2)/90(2)](2S). The results for static stiffness and strength as well as fatigue life and residual strength under different fatigue stress amplitudes were evaluated and compared with those of composite laminates made from other preforms. The damage and failure mechanisms of the composite laminates were discussed. The wear-out model was applied to fit the S-N curves and estimate residual strength of composite laminates, and good correlation was obtained. Compared to composite laminates made from pre-impregnated tape prepreg (e.g. APC-2), the commingled CF/PEEK composite laminates are much more sensitive to fatigue loading because of imperfect fibre bundle alignment. (C) 1997 Published by Elsevier Science Limited.