Strategic reinforcement of hybrid carbon fibre-reinforced polymer composites

A secondary fibre has been used to improve the impact properties of carbon fibre-reinforced composites. Steel wires possessing similar elastic properties to Type III carbon fibres have been added strategically to the composite cross-section. This has resulted in a 100% improvement in the fracture energy provided that the wires were placed in close proximity to the compressive or impacted face. Such a result is achieved with small increases in longitudinal and interlaminar shear strength. Only minor changes in specific properties occurred through the introduction of the high-density wires. The increase in fracture energy occurs because of the elimination of a compressive failure mode, believed to be brought about by the steel wires increasing the resistance to buckling at the impacted face. Hence, more energy-intensive processes, such as multiple delamination, fibre and wire pull out, are permitted to take place over larger areas of the fracture face.