Post-impact fatigue performance of carbon-fibre laminates with nonwoven and mixed woven layers

Woven and nonwoven carbon-fibre laminates were subjected to drop-weight impact at energies of up to seven joules. The damaged laminates were tested to differing periods of cyclic tension and cyclic compression fatigue. Static residual strength tests were then performed. The nonwoven composite showed greater losses in static strength after impact than the mixed woven composite, particularly when tested in compression. After tensile fatigue, significant improvements in residual strength were recorded, which coincided with the observation of micro-delaminations throughout the laminate. After compressive fatigue, there was little change in residual strength.