As the Marine Corps looks for answers to the deadly dangers of improvised explosive devices in Iraq, and the Navy seeks to protect ships from sea mines and anti-ship missiles, the Office of Naval Research is exploring radically new approaches to designing metals that could lead to effective blast shielding for military units--and protection for civilian targets against terrorist attack.
In an effort prompted in part by the October 2000 terrorist attack on the Navy destroyer USS Cole in Yemen that killed 17 Navy personnel, ONR's Engineering, Materials, and Physical Science division is sponsoring pioneering work at Northwestern University. A team of crack engineering students that calls itself Team BlasTruss is being led by veteran metallurgist Greg Olson to develop "recipes," or toolboxes for the design of super-hard steels.
ONR program manager Julie Christodoulou explains that metals aren't monolithic substances, but vary widely in composition and structure. Different types of steels are composed of crystal-like "micro-structures" that are neither uniform nor homogenous. Metallurgists typically develop new types of steel and other metals through trial-and-error by combining, for example, percentages of certain steels, nickel, and other known metals to produce the desired degree of strength, endurance, and other characteristics. That approach works backward from the structural level to determine the usable combinations of materials for desired applications. Instead, Northwestern's Team BlasTruss first identifies the desired characteristics of the steel. It then looks at elementary molecular-level composition of materials in order to determine the optimal mix of metallic ingredients needed to meet Navy requirements.
The BlasTruss team used available research data on metals to identify and demonstrate the performance of a new metal, designated BlastAlloy-160, for use in fabrication of a folded-plate truss, a blast-resistant steel structure that could be used in construction of a rugged vehicle such as the commercial Hummer, as well as a safe room, trash receptacle, and a Boeing 747 cargo bay. The team also has looked at the potential for using BA-160 for a blast-resistant luggage rack for trains that would protect passengers from the kind of blast that killed many of the victims of the Madrid bomb attack of March 11, Christodoulou says.
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