Spectrum - Volume 19 Issue 29 April 24, 1997 - Perforation-resistant material receives patent

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Perforation-resistant material receives patent

By Susan Trulove

Spectrum Volume 19 Issue 29 - April 24, 1997

A new material, developed at Virginia Tech for its potential applications for body and vehicle armor, has received a patent (Patent 5,614,305 issued March 25, 1997).

"A reinforced polymer composite material with embedded Nitinol fibers" was developed by Craig Rogers, former director of the Center for Intelligent Material Structures and Systems at Virginia Tech, and Jeffrey Paine, a graduate student with the center. The patent is owned by Virginia Tech Intellectual Properties (VTIP) Inc., a nonprofit corporation affiliated with the university.

Rogers, now dean of engineering at the University of South Carolina, explains that Nitinol is a shape-memory metal that can be stretched like a rubber band. It is used in eyeglasses frames to help them retain their shape, and in the wires on dental braces.

"When used as a fiber in composites, it allows the material to dissipate energy so it can withstand a great impact," Rogers said.

Paine, now vice president of engineering with Garman Systems of Nashville, Tenn., did his Ph.D. work in shape-memory alloys, including developing and testing the use of the Nitinol composite material for armor and composite-material pressure-vessel reinforcement. He and colleagues worked with both the Virginia Tech police department and the Army Research Office to determine environments in which the material would provide protection.

"The nitinol reinforcement works well with low-velocity impacts (200 feet per second) such as the type seen in handguns, aircraft birdstrikes, runway-debris impact, and vehicular impact," Paine said.

Nitinol-polymer composite's most effective use may be in toughening of airplane composite structures such as wings and fuselage, and in armor for cars and tanks.

"In airplanes, it could prevent damage from foreign objects, such as bird hits, or aid in containment of cargo-hold explosions. On armored vehicles, it would significantly improve protection against mine fragments."

Paine said he also sees potential for the new light-weight composite in personal body armor such as reinforcing Kevlar ((TM)) armor helmets. Research is still ongoing in these areas.

Fred LaLande, research assistant professor with Virginia Tech's Center for Intelligent Material Structures and Systems, said since Paine graduated in 1994, center researchers have started to model theoretical applications and have done ballistic testing, working with projectiles at 1,000 feet per second.

The patent will be marketed by VTIP Inc.