TWI Industrial Member Report 1170-2023 [pdf / 2099 KB]
By Chris Graham
Current technological demands are increasingly stretching the properties of traditional materials to expand their application into more severe or extreme conditions, whilst simultaneously seeking cost-effective production processes and final products. Limited multi-functionality has often prevented composites from being more widely adopted. In the aerospace industry metals are still incorporated into structures to impart mechanical integrity and electrical conductivity. It is well known that some surface treatments such as etching the fibre surface may enhance fibre/matrix interface adhesion and hence the stress transfer within the composite due to increased contacting area and possibly strengthened bonding. However, etching can also adversely affect the strength of fibres. The final properties of the fibre-based materials depend on the net contribution of these two opposing effects. It is therefore imperative to optimize the method and extent of treatment to gain the maximum possible enhancement in the performance of composite.
The use of composites within the aerospace industry has revolutionised design and resulted in significant fuel savings across many fleets. 20% of the Airbus A380’s airframe is composed of composites in areas including the wings, fuselages sections, tail surfaces and doors, and around 50% of the Boeing 787 is constructed from advanced composites, resulting in a 20% weight saving compared with aluminium. The lighter the aircraft, the less thrust required and therefore less fuel is burnt.
Lightweight composites enable reduced fuel per passenger, effectively reducing CO2 emissions and potentially perceived aircraft noise. Boeing have recently set up initiatives to recycle carbon fibres from decommissioned aircraft, and have reported that recycling carbon fibre can be done at approximately 70% of the cost and using less than 5% of the electricity required to make new carbon fibres. This highlights the additional advantages and sustainability impact of the development of carbon fibre materials for aerospace applications.
Conventional aircraft design requires the incorporation of Expanded Copper Foil (ECF) on some aerodynamic surfaces. This copper mesh is heavy. The integration of CNTs into carbon fibre and doped thermoset resin and additionally integrating nanotechnology for the surface multi-functionality, can provide a promising composite materials for lightweight aeronautical structures to reduce 20% or more of the weight of Expanded Copper Foil needed in the zones prone to lightning strike as per standards.
The same requirements for large aerofoil structures also largely apply to the wind turbine industry and the project is also relevant to the Automotive sector. The usage of CFs in braking, steering and suspension systems can be advantageous in reducing mass and increasing stiffness, enabling lighter weight design.