New body armor designs combine protection and comfort
One of the lasting lessons from a decade of war in the Middle East is that insurgent forces can impose huge costs on a larger, higher-technology adversary by targeting the force at all times, with actions ranging from sniper fire to counter-logistics attacks and rocket and mortar strikes aimed at vehicles and forward bases. The reaction of coalition forces has been a renewed emphasis on force protection, from body and vehicle armor to systems designed to defend against low-tech weapons. This two-part report examines recent advances in two areas, body armor and missile-killing defensive weapons, that play an outsized role in protecting troops and vehicles.
New materials promise improvements in the weight of body armor, but are unproven—and an alternative approach to the problem involves looking at whether some current systems are stronger and heavier than necessary. Technological progress tends to be incremental, but the U.S. Office of Naval Research (ONR) hopes to make significant advances with its “Lighten the Load” initiative to reduce the burden on U.S. Marines. Body armor is a critical target, as it is the single largest element of the load.
“We are taking multiple approaches to reduce the weight of PPE (personal protective equipment),” says James Mackiewicz, program manager in ONR's department of expeditionary warfare and combating terrorism.
One approach is to find improved materials for all applications. For example, the ONR is looking into “better ballistic fabrics, fabric system configurations, improved armor synergy and improved ceramics for small-arms defeat,” Mackiewicz says.
Another approach is determining whether the armor is suitable to the mission, or whether lighter-weight armor could do as well. “We are reevaluating the threats to Marines to ensure we provide the appropriate armor for the threat scenario,” says Mackiewicz.
Body armor usually consists of “soft-armor” garments with “hard-armor” insert plates. The soft armor, which defeats low-velocity rounds and shrapnel, is typically woven DuPont Kevlar aramid fiber, ultra-high-molecular-weight polyethylene or other synthetics. The inserts have a front face made of ceramic, usually boron or silicon carbide—among the hardest materials known—with a tough synthetic backing. Incoming rounds, even armor-piercing bullets, are deformed or shattered by the hard armor, and remnants are stopped by the backing material or soft armor.
Armor research tends to follow developments in materials science, and much of the current effort focuses on carbon nanotubes (CNT), a single sheet of carbon atoms rolled into a tube. In theory, CNTs could be made hundreds of times stronger than steel, but this would rely on manufacturing flawless tubes in bulk, which is not yet possible. However, smaller tubes can be produced in bulk, and these are used to reinforce soft and hard armor.
Amendment II of Salt Lake City was reportedly the first to market this technology. Its material, RynoHide, is a soft armor that is lighter than Kevlar fiber but reportedly provides superior protection. RynoHide was created in partnership with the Nano Institute of the University of Utah to develop carbon nanotubes for body armor. Amendment II will not discuss details at this stage, but the company's “secret sauce” appears to involve CNTs interwoven with conventional fibers.
Others in the same field include Nanocomp Technologies of Concord, N.H., which is working with the U.S. Army's Natick (Mass.) Soldier Center. Nanocomp developed a proprietary process to make a nonwoven textile made of millimeter lengths of CNTs bonded together. A version that is 0.25 in. thick reportedly stops a 9-mm. bullet, which suggests it outperforms Kevlar. The next stage will be incorporating the material into body armor sets.
CNTs are also the key ingredient of a program to improve hard armor at Natural Resources Canada's Materials Technology Laboratory in Hamilton, Ontario. This involves mixing alumina powder, silicon carbide and boron carbide powder with CNTs and forming them into ceramic plates via hot-pressing. Previous results suggest that the nanotubes make the ceramic tougher and less brittle without affecting its strength. Plates may crack after the first hit, but a nanotube-reinforced ceramic should stop multiple rounds. It would also be more robust and less likely to be damaged during handling, which is a serious problem, as plates can break if they impact hard surfaces.
Materials science may provide simpler solutions. Auxetix Ltd. of Devon, England, has tested prototype body armor made of auxetic material. This has the seemingly paradoxical property of expanding when stretched—or as one source puts it, becoming thicker perpendicular to an applied force.
Auxetics improve materials by adding springiness to them. CEO Patrick Hook says an auxetic fabric incorporating Kevlar aramid is more ballistic-resistant than the aramid fiber by itself, and it is cheaper, since it uses as little as one-tenth of the expensive, high-tech material, with the rest being nylon. He has developed auxetic body armor, as well as blast curtains and spall liners.
Hook says auxetic material is relatively straightforward to manufacture on standard looms. An existing technique called weft insertion adds the spiral element, and the material can be engineered to adjust tension, degree of stretch and other properties.
Hook's U.S. licensee is working with Xtegra, a material he developed, to produce auxetic armor for the U.S. Navy.
While better materials may cut weight by 10%, the second approach mentioned by Mackiewicz, using appropriate armor levels, could save 30% or more. A 2012 Rand Corp. study found that troops in Iraq and Afghanistan were burdened with armor heavy enough to stop much more powerful rounds than they encountered. The threat has been shrapnel and 7.62-mm rounds. “Current body armor provides excessive overmatch against those threats,” Rand says.
The study recommends modular armor with different protection levels. Current U.S. armor varies from a 6-lb. vest, which provides basic protection that can be scaled up with front, back and side ceramic inserts totaling 32 lb. to cover more of the body (including the neck and groin).
Rand recommends using software that would indicate optimal protection in a given situation, rather than automatically issuing the heaviest armor available. It tested a system that analyzes various parameters and says it is possible to create a smartphone app for the task. This app would allow a field commander to select a military occupation specialty, threat level and the percentage of injuries that should not exceed three on the maximum abbreviated injury scale. The app would then provide an appropriate body-armor protection level.
The report acknowledges that full modular armor would be a logistical challenge, especially if multiple plates are provided for each soldier.
Lighter armor will contribute to more mobile and capable troops and will help them stay cooler. Moreover, recent Navy research suggests that reducing loads can improve troops' cognitive ability.
“With continued weight reductions and better armor placement, we are expecting operational capability to increase by 20-30% over the next three years,” says Mackiewicz.