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GLARE is a "Glass Laminate Aluminium Reinforced Epoxy" FML, composed of several very thin layers of metal (usually aluminium) interspersed with layers of glass-fibre "pre-preg", bonded together with a matrix such as epoxy. The uni-directional pre-preg layers may be aligned in different directions to suit the predicted stress conditions.
Although GLARE is a composite material, its material properties and fabrication are very similar to bulk aluminum metal sheets. It has far less in common with composite structures when it comes to design, manufacture, inspection or maintenance. GLARE parts are constructed and repaired using mostly conventional metal material techniques.
Its major advantages over conventional aluminium are:
- Better "damage tolerance" behaviour (especially impact and metal fatigue, as the elastic strain is larger than other metal material it can consume more impact energy. It is dented easier but has a higher penetration resistance )
- Better corrosion resistance
- Better fire resistance
- Lower specific weight
Furthermore, it is possible to "tailor" the material during design and manufacture such that the number, type and alignment of layers can suit the local stresses and shapes throughout the aircraft. This allows the production of double-curved sections, complex integrated panels or very large sheets, for example.
While a simple manufactured sheet of GLARE will be more expensive than an equivalent sheet of aluminium, considerable production savings can be made using the aforementioned optimization. A structure properly designed for GLARE will be significantly lighter and less complex than an equivalent metal structure, and will require less inspection and maintenance and enjoy a much longer lifetime-till failure, making it a cheaper, lighter and safer option overall.
GLARE is currently (2004) the most successful FML, patented by Akzo Nobel in 1987 and now entering commercial application in the Airbus A380, which has recently received a full type certificate from the FAA and European Aviation Authorities. The patent cites as inventors Roebroeks and Vogelesang, two former professors at the Faculty of Aerospace Engineering, Delft University of Technology, where much of the R & D for GLARE was done in the 1970s and 1980s.
The fruition of FML development marks the end of a long history of research starting in 1945 at Fokker, where earlier bonding experience at de Havilland inspired investigation into the improved properties of bonded aluminium laminates compared to monolithic aluminium.
Later, NASA got interested in reinforcing metal parts with composite materials as part of the Space Shuttle programme led to the introduction of fibres to the bond layers, and the concept of Fibre Metal Laminates was born.
Further research and co-operation with Delft University, the Dutch Aerospace Laboratory NLR, Alcoa and various other companies and institutions led to the first FML, the Aramid-fibre based ARALL. This proved to have some cost, manufacturing and application problems (while it had a very high tensile strength; compression, off-axis loading and cyclic loading proved problematic).
As a footnote, GLARE is also the material used in the ECOS3 blast-resistant Unit Load Device. This is the only commercially available container shown to completely contain the explosion and fire resulting from a bomb such as that used over Lockerbie.
GLARE is currently produced by Cytec Engineered Materials in Wrexham, UK who supplies it to the Airbus A380 component manufacturing facilities at Stork Fokker in the Netherlands as well as at Airbus in Nordenham, Germany. Stork Fokker has opened a brand new facility next to its existing facilities in Papendrecht, the Netherlands. There Stork Fokker is able to produce Glare sheets of 4.5 x 11.5 m including the milling of doors windows etc. on a state-of-the-art 5-axis milling machine with a movable bed.
Glare has also been used in manufacturing of the cargo doors of the latest models of the C-17 Globemaster III.
- Vermeeren, Coen (Editor) Around Glare: A New Aircraft Material in Context Published by Springer, August 1, 2002 ISBN 1-4020-0778-7
- Vlot, Ad Glare: history of the development of a new aircraft material Kluwer Academic Publishers, 2001 ISBN 1-4020-0124-X
- Morinière, Freddy D.; Alderliesten, René C.; Tooski, Mehdi Yarmohammad; Benedictus, Rinze (26 July 2012). "Damage evolution in GLARE fibre-metal laminate under repeated low-velocity impact tests". Central European Journal of Engineering 2 (4): 603–611. doi:10.2478/s13531-012-0019-z.