"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 says.
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, and runway debris impact, and vehicular impact," says Paine.
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."
He also sees potential for the new light-weight composite in personal body armor such as reinforcing Kevlar (TM) armor helmets, Paine says. Research is still ongoing in these areas.
Fred LaLande, research assistant professor with Virginia Tech's Center for Intelligent Material Structures and Systems, reports that since Paine graduated in 1994, center researchers have started to model theoretical applications and have done ballistic testing, working with projectiles at 1000-feet-per-second.
The patent will be marketed by VTIP, Inc.
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