One thing the war in Iraq has taught the military and its suppliers is that the threat - and the enemy that poses it - is no longer clearly defined. Armor manufacturers are being called upon to design protective systems for vehicles and personnel that can meet not only increasing levels of threat, but also withstand damage delivered by a variety of weapons wielded by unlikely combatants. Pressure is on, as well, to reduce armor system weight for security forces, military and civil, that require high mobility and maneuverability in environments as varied as open desert and congested urbanscapes. As a result, fiber-reinforced composites are earning a larger role in protective systems, supplanting or supplementing legacy systems that rely on metals and ceramics. Today, says Karl Chang, a research associate at DuPont Advanced Fiber Systems (Wilmington, Del), armor design must meet multiple functional requirements: in addition to ballistic performance, the system must meet weight limits and, when incorporated into vehicles, also fulfill structural requirements. Further, armor systems must account for what the industry calls "over-matching threat." "Over-matching threat means if I design an armor system, I have to design for a specific threat, but can't guarantee that the enemy will only shoot at me at the specification I am designing to, so I must be prepared to deal with that," Chang says. "That" can be armor-piercing bullets (called rounds by insiders) or terrorist bombs and incendiary devices. The latter, which armor designers categorize as improvised explosive devices (IEDs), not only deliver a blast load and projectile fragments but often include a fireball as well, says Chang, who notes that flammability has become a significant issue in armor design. "We can look at reports from Iraq in terms of soldier injuries, and there is a large number of burn injuries," he says.
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