Composites revolutionise aircraft wing production

The cost of using carbon fibre composites in civil aircraft wings could be dramatically reduced by new materials technologies being developed in the UK.

The use of composite materials in aircraft is increasing, and a research team at Qinetiq will be looking into technologies such as resin infusion, which will help to reduce the manufacturing costs of building carbon fibre components, said Deborah Pullen, group leader for the Cascade project at Qinetiq.

‘When compared to metals on a weight for weight basis, composites have always been seen as more expensive, but the cost of the material is only one part of the overall cost of a system or component.’

Existing techniques for using composites in aerospace components involve a pre-impregnated fibre from which the required shapes are cut out, laid in a mould and oven-cured to make the part.

In the new technique, dry fabric is used, and the shapes are cut and prepared before the resin is squeezed into the fibres using air pressure. This cuts down on the time taken to make the parts, said Pullen. ‘Manpower is a huge cost, and anything that helps to reduce that will make it much more cost effective.’

Resin infusion techniques are already used in the marine and construction industries, but predominantly with glass fibre, rather than the lighter carbon, and the tolerances required in these industries are lower. ‘For use in aerospace, the material has to be carbon, and there are some differences in the infusion methods needed for carbon and glass. The tolerances obviously have to be very good.’

The research team is also looking into the use of non-crimp fabric materials, where three or four layers are laid in one go, and stitched together. This technique holds the layers together without pinching the fabric, and again reduces the manufacturing time and manpower needed, said Pullen. ‘Until now many structures have been over-designed, as there is obviously a tendency to be conservative in building aircraft, but there is now a real need to start designing for composites.’

Qinetiq has been given £1.8m by the Department of Trade and Industry and Airbus UK for its research into polymeric materials as part of the £2.6m Cascade project.A spokeswoman for Airbus UK said the research was aimed at future generations of aircraft, rather than existing projects, but that any developments considered to be of benefit could be applied to aircraft already in service.

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