Sound used to help construct objects

http://www.vny.com/cf/News/upidetail.cfm?QID=183066

Saturday, 5 May 2001 0:30 (ET)

ATLANTA, May 5 (UPI) -- A manufacturing process that uses low-intensity
sound to move and arrange objects into shapes may one day help astronauts
build things in space rather than transport them from Earth.

Led by aerospace engineer Narayanan Komerath, a team of researchers at Georgia Institute of Technology in Atlanta has developed a way to use low-intensity, audible-frequency sound to corral objects into the shape of a wall. The device, into which raw materials such as Styrofoam shells are
placed, is a rectangular box with speakers and amplifiers attached to it.

"We started out experimenting with pieces of Styrofoam, then tried Rice Krispies cereal because of its shape and porosity," said Komerath.

"We then experimented with hollow aluminum and aluminum oxide spheres which could be used for space applications to build heat shields for example."

"What is surprising is that according to theories, you would think that if you put a lot of particles in the box and subjected them to sound they would clump around a single point. But instead we saw they distribute themselves in walls with shapes."

He said that by moving speakers to selective spots, researchers can adjust somewhat that distribution process.

Because it is expensive to ship goods into space, astronauts need to build what they need while in orbit. Some materials that might be useful in space -- especially those with components measured on the nano scale -- are highly difficult to control.

"One thing that's not clear is how you hold up a wall of [material] that is only one molecule thick," he said. "The materials are basically so small they can't support their own weight when you are making them."

Enter the sound system. Not only does it arrange cereal and Styrofoam, it also causes liquids to form a vertical wall. By adding nanosized powders to a liquid such as an epoxy, then applying sound, a super-thin wall can be created. The epoxy stands up inside the box like a sheet (or wall). As that
happens, the nanomaterials bind together. The liquid is allowed to evaporate, leaving behind a sheet of the nanosized particles.

"The sound creates a region of pressure difference that the water gets sucked into, causing it to stand up," he said.

The researchers have tested the device aboard NASA's KC-135 aircraft, which is capable of mimicking for brief moments the gravity-less environment of space. But Komerath said that the plane only gives about 20 seconds of low gravity experience, which is not enough to let an epoxy harden. To avoid those problems, he is working to miniaturize the device and test it in space. NASA has agreed to take a prototype of the sound box on a space shuttle mission set for March 2002.

High costs have caused NASA to shun manufacturing operations in space, said Komerath. But he said his device would be a lightweight construction tool that could work with various raw materials stored on board the space station.

"They would have some resin, for example, and supplies of hollow aluminum spheres," he said. "By using sound and tweaking the shape of the chamber, astronauts could arrange the spheres in the form of a panel. Then they could
use solar radiation to heat the panel and make the spheres bind together. This is all in the future, however. I don't see this happening anytime soon."

"I can appreciate the potential value of the concept," said Bill Wailes, president of STW Composites, an aerospace design company in Montrose, Colo. "Forming raw materials in micro-gravity will be a key part of the maturation of orbital infrastructure. Whether it's sonic shaping of solids or beam
consolidation of liquid media, the concept is and will become more valuable."

(Reported by UPI Technology Writer Kelly Hearn in Washington.)
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Copyright 2001 by United Press International.
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