Advantages and Disadvantages of Using Composite Materials in Airplanes
Composite materials—especially those made from glass fibers, carbon fibers, and Kevlar—are widely used in the aircraft industry. They are stronger and lighter than aluminum, the metal that's most commonly used in aircraft bodies.
Composite materials are so named because they consist of two or more materials. The composites used in planes consist of fibers suspended in a matrix of epoxy resin.
Fiberglass is a composite material made of glass fibers and epoxy resin. It was first used in aircraft, by Boeing, in the 1950s. The Boeing 787 Dreamliner was the first commercial airplane to be constructed from 50% composite materials, mostly carbon fiber composites; All Nippon Airways put the first 787 into service in October 2011. The remainder of the plane consists mostly of aluminum, titanium, and steel.
Composite materials have revolutionized aviation, but their use does present some engineering and maintenance challenges. Here is a roundup of the advantages and disadvantages of using composites in aircraft.
Weight reduction is the single greatest advantage of composite material usage. A lower-weight plane is more fuel-efficient because it requires less fuel to propel itself forward.
Composites are also incredibly strong and as a result have a higher strength-to-weight ratio, also known as specific strength, than the metals used in making aircraft. In addition, they resist compression and don't easily break under tension.
Composite materials aren't prone to corrosion due to harsh chemicals, and they're resistant to many highly reactive chemicals. They can also handle wide variations in temperature and exposure to severe weather.
Another big advantage of composites is their design flexibility: They can be made into just about shape. And a single, oddly shaped piece of composite can replace many pieces made of other materials. That helpful characteristic cuts down on maintenance and so can reduce costs over the lifetime of a plane.
Once a composite piece has been formed, it maintains its shape and size. That's important in the aircraft industry because it means the essential parts of a plane made out of composite materials won't grow, shrink, or change form as environmental conditions vary.
Perhaps the biggest disadvantage of composite materials for aircraft and component manufacturers is their higher initial cost compared with metals. The greater cost is largely due to the price of the fibers and the complicated process required to make the finished materials.
It can be difficult to tell when the interior structure of a composite aircraft piece has been damaged. That makes inspections difficult and more costly.
One issue that comes up during inspections is delamination—when layers of composites separate. The biggest cause of delamination is an impact to the composite piece. Water can infiltrate a piece that has experienced delamination, and the problem will get worse as the water freezes and thaws.
Standard aircraft composite materials do not conduct electricity and so, unlike aluminum, can not prevent lightning from being directed to a plane's fuel tanks. That problem was corrected for the 787 by incorporating wire mesh into the composite.
Finally, the resin used in composite materials weakens at temperatures as low as 150 degrees Fahrenheit, and a temperature above 300 degrees might result in aircraft failure. When composite materials burn, they give off toxic fumes and micro-particles into the air, causing health risks. For all of those reasons, fire prevention is crucial on planes built with composites.