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Improving composite wing part manufacture

Our modelling and testing methodologies have improved the manufacturing process of commercial aircraft wings, resulting in better quality parts.

Professor Richard Butler looks through a wing section prototype.
Faults during the manufacturing process can be economically and environmentally costly.
‘Our research collaboration with GKN and Airbus has reduced the scrappage rates for defective parts. This has significant consequences for protecting our environment by using fewer resources and reducing CO2.’
Richard Butler Professor of Aerospace Composites and GKN Royal Academy of Engineering Research Chair

The A350-XWB was the first Airbus airliner to use composite wings. Unlike traditional metallic wings, composites combine multiple materials for greater strength, lower weight and better durability. Lighter wings mean savings in fuel, CO2 and operating costs.

Anticipated as one of the world's most modern and efficient aircraft, Airbus received over 700 orders for the new A350 and its revolutionary adaptive wing design. Airbus needed to increase production rates to meet this high demand and were keen to optimise processes while mitigating manufacturing risks.

Composite wing design and manufacture

For over 25 years, Airbus and the University of Bath have worked together on composite analysis and design methods. Alongside GKN Aerospace, Airbus’s manufacturing partner, we set out to reduce scrappage of defective parts and improve strength testing for wing spars.

The A350’s wing is made from carbon-fibre reinforced plastic, a lightweight carbon composite. This is created by arranging microscopically thin carbon fibres into a matrix with a resin and then subjecting this to intense heat and pressure. The result is the production of laminated skin panels, which can be layered to create a very strong, but lightweight structure.

A 30-metre wing can be over 100 layers thick in some places and only ten layers thick in others. The fibre orientation within each layer, as well as a layer’s thickness, are crucial to a wing’s design. Any defects in the production of these laminated skin panels compromise the safety of the final product and must be discarded. This costs GKN both time, money and resources.

Process improvement for wing spars

A major structural component within a wing is the spar. This spans the entire wing and acts like the structural backbone.

The laminated rear spar of an A350-XWB is manufactured by robots on an automated production line. If a fault occurs during this process there is a risk of buckling or wrinkling in the layers, which would reduce the strength of the finished spar.

Our researchers analysed the laminate consolidation process for wing spars and adapted mathematical models for geological folding to predict fibre wrinkling during manufacture. Using this method, GKN was able to minimise defects and so improve spar part quality.

We also used mathematical modelling to analyse and develop a new process of testing wing spar strength. Our new edge treatment process, where a tough resin layer is bonded to the edges of a test specimen, produced results more representative of the stresses at play within the real-world environment of a wing. This resin helps to achieve a realistic failure mode consistently for coupon level tests.

Testing wing spar strength

Using supercomputers we can model to the thickness of a human hair to help test the virtual strength of carbon fibre during production.

Economic and environmental impact

Our work with GKN and Airbus helped to optimise the manufacture of composite wing spars, while taking into account strength and design requirements.

The new edge treatment process, which was validated using Bath's numerical modelling expertise, helped GKN to salvage defective spars which would otherwise have been scrapped. At that stage of production, this saved up to £60,000 per wing spar, leading to initial savings of £11 million and 1,200 tonnes of CO2.

‘Our new processes, supported by Bath’s fundamental research, have enabled us to increase production rates for the A350 to meet higher commercial requirements.’
Kostas Soumilas Senior Vice President, Engineering & Technology - Civil Airframes, GKN Aerospace

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Mechanical engineering research