Composite materials are extending their reach. As the name indicates, composites are a combination of several different materials. Generally made of a fiber-based reinforcement (glass or carbon fiber) and a binder (epoxy type resin, for instance), they offer fabulous possibilities in air and space applications. With half the density of aluminum (one of the lightest metals), composites offer considerable weight savings. “On the A380’s nacelles, composites allow 3,000 pounds in weight savings compared with conventional materials,” explains Patrick Girault, Vice President Strategy and Development at Aircelle. “And by saving structural weight, the aircraft can carry more payload.”

In addition to lightness, organic composites are also a key to reducing noise and increasing reliability. They may reduce noise by up to 10 or 20 decibels. For instance, engine nacelles use a honeycomb sandwich structure, in which two composite material “skins” enclose a cellular filler that absorbs sound.

Stronger too!
The third major advantage of composites is fatigue resistance and better reaction to shocks, as Girault explains: “A shock on an aluminum structure will produce a crack that subsequently propagates. With a composite, there is no propagation.” The part thus offers longer service life and greater damage tolerance.

In other words, the future of composite materials is guaranteed, and there is still considerable headroom for growth. Composites are already used on 40% of the nacelles designed and produced by Aircelle, and the percentage could reach 50% according to Girault. Aircelle is betting even more heavily on composites because it is teaming up with fellow SAFRAN Group companies on other projects that will make use of these qualities.

Over the last ten years, for instance, Snecma has called on Aircelle’s Le Havre plant to make the acoustic liners for the CFM56, as well as the bypass ducts for the M88 military engine. With Messier-Dowty, Aircelle is developing composite struts for the Boeing 787 landing gear, overturning the traditional supremacy of steel and titanium.

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