Search Continues For Lighter Alternatives to Steel Armor

Becoming a lighter and faster force — Army officials have iterated endlessly — is among the service’s paramount goals. But the Army may have a tough time getting there as long as tons of heavy steel plates continue to bear down on its patrol and combat vehicles.

Lighter blast-proof materials that can protect vehicles as effectively as steel have been a continual pursuit at military and private sector laboratories, but so far success has been limited. While lots of exotic new armor materials have emerged, the military remains mostly committed to the rolled homogeneous armor steel for its combat vehicles — generally because of its proven protective qualities and its relatively low cost compared to next-generation technologies.

The Pentagon’s science arm, meanwhile, believes that there may be practical solutions out there — from nameless small businesses or even from someone’s garage — but that the military has yet to reach out and grab them.

That was the thinking behind the “armor challenge” sponsored by the Defense Advanced Research Projects Agency. Two years into it, DARPA boasts that it has tested at least 50 new technologies and that, so far, several of them were judged to perform well enough to merit further evaluation and government funding.

Leo Christodoulou, who oversees the armor challenge at DARPA, says this project is nothing like most traditional military research undertakings. In the armor challenge, the government does not fund research and development work but instead offers to test existing technologies and, based on the results, may choose to pay for additional trials and even provide guidance to companies so they can make their products available to military agencies.

Under this approach, DARPA acts as a mentor to companies or inventors who would otherwise never have a shot at a military contract. “We give them seed money to turn their idea into reality,” says Christodoulou. “DARPA purchases the test articles and pays for tests, but is not funding any research and development efforts.”

Traditional military contractors already are engaged in a litany of armor research projects at various defense agencies. But Pentagon officials for years have insisted on the need to recruit lesser-known firms that can inject innovation into military programs. “We want to engage new people,” Christodoulou says. “The armor challenge is aimed at non-traditional companies … It’s aimed at small businesses, at inventors in their garage.”

DARPA officials instinctively suspect that some of the answers to the Army’s armor problems may come from companies or individuals who currently lack the means to present or market their technologies to the Defense Department.

For the armor challenge, bidders send concept papers to DARPA. Those that are selected receive funding to manufacture an armor sample plate or armor panel that will then be put through a series of shootouts at a certified ballistics laboratory, at DARPA’s expense.

During the past two years, DARPA has received dozens of armor design proposals, but only 50 were deemed worthy of further investigation. Five made it to the “detailed evaluation” phase.
The armor challenge originally was supposed to end in January 2008, but DARPA has decided to extend it for a third year.

Awards range from a few thousand dollars to millions. The bidders retain the rights to their intellectual property, although classified test data are withheld from armor challenge participants if they do not hold the appropriate security clearances.

Christodoulou declined to discuss the pros and cons of specific products submitted for the armor challenge. Broadly speaking, he says, the more successful proposals are those that present new ways to employ already accessible materials.

“What excites us is that they are not new or exotic materials but rather interesting new ways of arranging existing materials,” says Christodoulou. “We are not looking for unobtainium.”

Part of the mystery of armor is the layering of various materials — metals, composites or ceramics — so that the collective result is a plate that can stop a fast-moving projectile. 

“The way they mix and match materials is what attracted us to the proposals that were selected,” says Christodoulou. “We are encouraging innovative uses of easily available hard and soft materials.”

The primary goal for the armor challenge is a 50 percent reduction in weight compared to rolled homogeneous armor steel for protection against 7.62 mm armor piercing rounds and 0.50 caliber projectiles. A secondary objective is to be able to produce vehicle armor materials at a cost competitive with, or less than, RHA steel.

Those organizations whose concept papers are selected must deliver three 18-inch by 18-inch armor panels for each threat. The ones that can provide protection against the range of threats using a single configuration will be evaluated more favorably, according to DARPA.

One start-up firm that was selected for the armor challenge claims that it has successfully applied tenets of nanotechnology to produce materials that can provide the same level of protection as steel for half the weight.

The materials, dubbed nano-laminated alloys, can be added to the core structure of a vehicle to make it even more resistant to enemy fire, therefore reducing the need for add-on appliqué armor, says Christina Lomasney, scientist and founder of Modumetal, based in Seattle.

The materials in nano-laminated alloys are measured on a nanometer scale, she explains. “We are using this approach to try to create harder materials that can absorb more energy at a lighter weight.”

This approach differs from the more widely used armor designs that employ ceramics in add-on armor plates. “We use structural materials. That’s contrasted with ceramics, which are non-structural — they have to be added,” Lomasney says.

Even vehicles that rely on steel armor can save weight if the metal can be incorporated as part of the chassis of the vehicle. Composite armor and ceramics weigh less than steel but the materials are not strong enough to be part of the structure, she says. “Ceramics and plastic composites can’t carry loads the same way that steel can.”

With nano-laminated alloys as part of the structure of a vehicle, Lomasney believes, the weight can be cut in half compared to RHA.

In a vehicle that weighs 40,000 pounds, if half of that weight comes from armor, the lighter alloys would help slim it down to 30,000 pounds while maintaining the same ballistic performance, she says.

Another company that got a boost from DARPA’s armor challenge — CPS Technologies based in Norton, Mass. — is betting on a “hybrid composite armor” as the answer to lighter vehicles.
The technology combines a ceramic tile with a metal matrix composite, says Rich Adams, company vice president.

“Ceramics are very brittle but very hard … they can break up armor piercing munitions,” he says. “We make them into composites to make them much harder.” Both the Army and major defense contractors seem “very interested” in this technology, Adams says.

The hybrid composite armor that CPS developed, he estimates, could weigh half as much as steel. But the company is still trying to figure out how to lower the cost of producing this new armor. Often ceramics are considered too expensive for light-skinned ground vehicles such as trucks, he says. “If there are airborne applications, such as helicopters, they are more willing to pay for it.”

Adams says one variant of the hybrid armor has hard ceramic in the interior of a composite structure, and aluminum at the exterior. Other components can also be included, he says. “An infinite number of combinations can be created with this technology, at various price and performance points.”

The company has yet to prove it can make this armor for less than the cost of high-end silicon carbide ceramics, which the Army has been acquiring in recent years. Less expensive armoring materials include boron carbide and aluminum oxide. “Silicon carbide can cost 10 times as much as aluminum oxide. It’s possible that our solution would be less costly than both. If the packing is simpler, the overall cost can come down.”

Integrating the ceramic into the armor structure is what adds to the cost, says Adams.

Like Lomasney, he believes that to lower the weight of a vehicle, the key is to use armoring materials that can become part of the structure and therefore reduce the need for appliqué armor.

“Armors are parasitic. They offer no structural benefits, they only offer protection,” Adams says. “It’s possible that with new materials they can become part of the structure and less parasitic.”

DARPA’s Christodoulou concedes that the odds are stacked against most armor challenge proposals. That said, even some of the most unlikely candidates can deliver unexpected results.

Unless someone gives these ideas a chance to prove themselves, the military may lose out on worthy innovation, he says. “It’s a ‘Hail Mary’ approach.”

Topics: Science and Engineering Technology, DARPA