CAMBRIDGE, Mass. -- In recent years, many airplane manufacturers have started building their planes from advanced composite materials, which consist of high-strength fibers, such as carbon or glass, embedded in a plastic or metal matrix. Such materials are stronger and more lightweight than aluminum, but they are also more difficult to inspect for damage, because their surfaces usually don't reveal underlying problems.
"With aluminum, if you hit it, there's a dent there. With a composite, oftentimes if you hit it, there's no surface damage, even though there may be internal damage," says Brian L. Wardle, associate professor of aeronautics and astronautics.
Wardle and his colleagues have devised a new way to detect that internal damage, using a simple handheld device and heat-sensitive camera. Their approach also requires engineering the composite materials to include carbon nanotubes, which generate the heat necessary for the test.
Their approach, described in the March 22 online edition of the journal Nanotechnology, could allow airlines to inspect their planes much more quickly, Wardle says. This project is part of a multiyear, aerospace-industry-funded effort to improve the mechanical properties of existing advanced aerospace-grade composites. The U.S. Air Force and Navy are also interested in the technology, and Wardle is working with them to develop it for use in their aircraft and vesselsAdvanced composite materials are commonly found not only in aircraft, but also cars, bridges and wind-turbine blades, Wardle says.
One method that inspectors now use to reveal damage in advanced composite materials is infrared thermography, which detects infrared radiation emitted when the surface is heated. In an advanced composite material, any cracks or delamination (separation of the layers that form the composite material) will redirect the flow of heat. That abnormal flow pattern can be seen with a heat-sensitive (thermographic) c
|Contact: Caroline McCall|
Massachusetts Institute of Technology