SSS 2011-03-28

（单词翻译）

This is Scientific American's 60-Second Science. I'm Cynthia Graber. This will just take a minute.

Airplane manufacturers have been changing over from aluminum¹ to advanced composite materials. These lighter², stronger composites are made of fibers³ of carbon or glass embedded⁴ in a second material, often plastic.

One advantage is that composite-based planes use significantly less fuel. But there's an important disadvantage. When aluminum is hit, you can see a dent⁵. Composites, though, spring back to the original shape, which could hide internal damage.

One technique to test composite material takes advantage of heat transfer: inspectors⁶ place large heaters next to a section of the plane. Any cracks will alter the flow of heat, and these changes can be picked up with a heat-sensitive camera. But this involves bulky and expensive equipment.

Now MIT researchers have designed a new system. All you need is carbon nanotubes included in the composite. Because nanotubes will heat up in response to a small electric current. This can be produced with a hand-held device. Any internal deformations⁷ will still change the heat flow, which can be picked up by the thermal⁸ camera. The research was published in the journal Nanotechnology.

This technique offers the ability to detect very small cracks—which could help keep passengers safer in the skies.

Thanks for the minute. For Scientific American's 60-Second Science, I'm Cynthia Graber.