Striking out with materials R&D

Materials World magazine
,
3 Apr 2011
Lockheed Martin F-35 Lightning II Joint Strike Fighter

Dan Kells, Technology Consultant, and Dan Jones, Network & Communications Manager, for the Aerospace, Aviation and Defence Knowledge Transfer Network, reveal the scope of the KTN’s Materials and Structures National Technical Committee.

At the heart of any thriving industrial sector is a willingness to engage in collaborative R&D programmes to exchange expertise, knowledge, capabilities and assets for the development of technologies and advancement of the sector.

The Materials and Structures National Technical Committee (M&S NTC) of the Aerospace Aviation and Defence Knowledge Transfer Network (KTN) is a forum set up to enable and identify programmes of collaborative R&D that is fundamental to achieving future performance requirements. It looks at the tri-service defence sector, as well as civil aerospace, and other cross-cutting themes, such as space, and has stakeholders from across the industry sectors, as well as universities, research and technology organisations, funding bodies and specialist independents.

One of the Committee’s strengths is its ability to present a consensus viewpoint of businesses that, ordinarily, would be natural competitors.

Here they provide a united front to articulate the critical capabilities that the UK must develop to stay competitive in the face of shifting economic, environmental and social global market drivers for the aerospace and defence sectors.

A key output is a series of UK air vehicle technology reviews that appraises the state of the technology and details priorities for future investment. The first review on Combat Aircraft for Strike, Air Defence, Surveillance and Training outlines underlying UK equipment philosophies and the size and importance of this market. The defence market, including exports and domestic sales, is worth £11.6bn.

Design and manufacture

Trends in structural concepts and design, materials choices, manufacturing development and operational issues are identified against three time frames – current and recent history, the next five years, and those perceived over a 20-year horizon. This enables common drivers for research to be identified over the same time frames, supporting equipment in use, requirements stemming from offshore equipment acquisition, technology insertion, and design and manufacture of defence equipment. Against these basic drivers, approximately 30 broad areas for potential R&D are outlined.

Flying high

Military wing technology has been a strong part of the UK’s aircraft capability in recent years. BAE Systems has been heavily involved in producing composite wings for the Eurofighter development aircraft, while Airbus fabricates the hybrid wings for A400M, which is considered in a parallel review. Such manufacturing has been dominated by metal structures and their mid-life upgrades, but new wing production will exploit a larger percentage of composites.

In terms of upgrades to operational platforms, prime examples can be found in the re-winging of the Hawk and Tornado. Traditionally, wing box construction comprises three main structural parts – the spars, the ribs and the skins. Future designs, using composite materials, may use radically different approaches to achieve the necessary structural stiffness and strength. In particular, conventional stringer stiffened skin, spar and rib design philosophy is being challenged by concepts such as geodetic configurations, stabilisation by lightweight foam and rib-less forms.

Fine tuning techniques

Another area considered is manufacturing processes. Metallic manufacturing will still be based on traditional techniques, such as casting, forging, machining, forming and welding.

Each technique has its own specific requirements and there is a real need for low cost, flexible tooling. Additive manufacturing techniques for metals can eliminate tooling and reduce costs for fabricating of small numbers. This is particularly attractive for development and support purposes, for example, using lasers to scan and then build replacement items in the field, eliminating the need to hold stocks. This has been under evaluation for engine components for some time.

New structural assembly techniques are also being considered and may be adopted in primary structures. Typical examples include friction stir and laser welding of metal structures, and rapid metal deposition for repair or new structures. The structures’ performance, reliability, endurance, and inspectability require an increasing level of competence as the techniques near application.

Composite manufacturing processes are highly specific to each application. A suite of cheaper, faster techniques is superseding traditional autoclave manufacture, for example, tape laying, fibre placement or resin infusion. When these are combined with flexible assembly techniques, such as co-cured or mechanised assembly, high performance components and sub-structures can be produced.

In future, manufacturing techniques that match the virtual design process are envisaged to be adaptive, or robotic, so materials of selected function and performance are deposited or laid down as usable structures. Looking further ahead, the capability to robotically build hybrid materials into structures is expected to become more mature – this will become important as the traditional bulk manufacture of large quantities of stock material for subsequent conversion into structure will not be efficient or sustainable.

A chance for collaboration

Although this review focuses on combat aircraft, reviews will touch on – and cut across – other areas of the sector, including civil aircraft, unmanned aerial systems, engines and powerplants, rotorcraft and future concepts. While each review concentrates on UK capabilities, they will also consider both national and international opportunities for collaboration and how to achieve greater engagement across the materials community.

The M&S NTC is open to contributions, suggestions and potential collaborations. The reviews will be updated and re-published periodically to reflect changes in technology, the markets and operations. 



Further information

To receive a copy of the UK Air Vehicle Technology Review for Combat Aircraft you need to register free of charge online at www.aeroktn.co.uk/register, and then go to https://ktn.innovateuk.org/web/materials-and-structures-ntc/document-library to download the review as a PDF file.