From Train Track to Space Station : Lab Hopes to Develop ‘Smart’ Materials

Bridges, buildings, trains and planes that monitor their own structural well-being sound like science fiction, but they are the results of new technology that lets scientists test things without destroying them.

“Our work is like reinventing the wheel and making it work better,” said physicist Joseph S. Heyman, who runs the Non-Destructive Evaluation Laboratory he started in 1971 at NASA’s Langley Research Center.

The lab uses an array of measurement techniques--thermal diffusion, ultrasonics, acoustics, magnetism, X-rays, lasers and holography--to probe for internal defects in objects like space shuttle solid rocket motors, satellites, airplane wings, train wheels and railroad tracks.

Then there are “smart” materials that take care of themselves.

“We’re investigating how to incorporate sensors directly into materials,” Heyman said. “It’s easy with fiber-like materials like composites: A fiber optic line is buried in the structure. An aircraft wing can be made the same way, and the same applies to larger structures like the space station.”

The technology is especially critical for the space station expected to be built in the 1990s because it will be a permanently orbiting platform bombarded by cosmic dust and stressed by extreme temperatures. Less glamorous would be its use in bridges, buildings, oil platforms and pipelines, “anything where you need to measure strain, stress and temperature,” said Heyman.

Smart materials will sense that something may be malfunctioning before a major problem develops, he said. “This nervous system we’re building will be able to sense when we need help. I’m talking about the whole structure as a sensor. It can measure with phenomenal sensitivity.”

A U.S. Transportation Department scientist recently finished 1 1/2 years at the lab trying to figure out how to prevent derailments through early detection of cracks in train wheels and tracks, the main cause of derailments.

The NASA facility also has focused on engines falling off aging airliners, using a variety of techniques because the problem involves corrosion as well as cracking in engine mounts.

Other results of the lab’s efforts include the use of high-resolution ultrasonic monitors to measure how heat spreads through the materials used in stereos, computers and TV sets. That could lead to “a stereo that will last beyond your life.” Heyman said.