Mechanical properties of auxetic carbon/epoxy composites: static and cyclic fatigue behaviour

This work describes the effect that stacking sequence lay-ups have on the static and cyclic fatigue properties of T300/914 auxetic carbon/epoxy composites. Two laminate composites [±20]2S and [±25]2S providing a theoretical NPR effect through the thickness have been subjected to quasi-static and cyclic fatigue under 3-point bending. The static tests have shown that the stiffness and the maximum failure load decrease with increasing fibre orientation angles for the laminates. The fatigue tests also show that the stiffness degradations versus the number of cycles occur on tree stages, with significant energy dissipation recorded for the two auxetic specimens