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Soldier Gear
Army’s Procedures for Testing Body Armor Stir Controversy
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By Sandra I. Erwin
The Army is overhauling its methods for testing body armor plates. The revised test procedures are causing consternation among contractors because their products are now experiencing higher failure rates.
But even though fewer plates are passing tests, Army officials insist that there is nothing wrong with the armor that was shipped to deployed units before the test procedures were changed in February 2009.
Suppliers of military body armor are now required to have all plates tested at the Army’s Aberdeen Test Center in Aberdeen, Md. Before the new policy took effect, companies were allowed to have their products tested at private labs that are certified by the U.S. National Institute of Justice and are used by law enforcement agencies.
The changes followed a damning report by the Defense Department’s inspector general that found that three of eight armor designs that originally had passed NIJ-lab testing actually failed. As a result, the IG recommended that the Army recall 16,413 body armor plates.
The new testing regime at Aberdeen is resulting in higher failure rates, which means that companies must discard millions of dollars worth of plates that would have passed the NIJ lab tests.
“In some instances, the ATC testing is more rigorous than the NIJ labs,” says Army Col. Jeffrey P. Holt, commander of the Aberdeen Test Center.
“Some of the armor is experiencing difficulties,” Holt says in an interview. A relatively small percentage of plates that would have met the NIJ standards are failing under the military testing protocols, he says.
An example of how tests have changed is the way clay blocks are handled. Clay blocks are used to simulate human bodies in tests. NIJ standards are not as strict as the Army’s on how long a clay block can be out of the oven before it’s shot, or how many shots can be put on it, says Holt. “We put in place standards that are less open to interpretation,” he says. “I don’t think we changed the grading standards but better defined how the test event takes place.”
Another source of discontent among vendors is the way the Army is now measuring a plate’s “back face deformation” — a term used to describe the effect of a non-penetrating projectile on the rear face of a strike plate. The extent of allowable deformation set by NIJ is 44 mm.
Previously the cavity created on a plate by the impact of the projectile was measured with calipers. One of the key requirements for hard armor is to minimize the depth of the cavity that occurs behind the armor, as the energy doesn’t stop at the plate, and continues into the human body. Calipers could not accurately measure that cavity after a shot, Holt contends. The Army switched to a laser scanner that more precisely maps, captures the deformation image and measures the deepest point of the penetration, says Holt. “Previously we found the caliper couldn’t measure the cavity with repeatable accuracy.”
Marc King, vice president of armor manufacturer Ceradyne, says the company has “serious issues with the way some of the testing is conducted at ATC.” The way ATC measures back face deformation is a sore point of contention. The width of the head of the caliper used in the NIJ certified range is 3.7 mm, while the ATC laser tool head measures .7 mm. “Routinely you get back face deformation numbers that are 2 mm higher than under the old measuring technique,” says King. “The laser also looks into features that were not discernable using the NIJ measuring method.”
This is a huge headache for vendors, he says. “You developed a product based on an old method of measuring.”
But so far armor suppliers have not been told that they have to redesign their plates.
More armor is being rejected but that does not mean that plates that were shipped to soldiers before the new testing protocols were in place are defective, cautions Holt. “There’s a large buffer built into the requirements for pass/fail,” he says. “There’s a big margin of safety,” he adds. “The results we’re seeing with laser versus caliper are not light years different. In many cases the differences are small.” The test results don’t call into question the fundamental design of the plates, Holt says. He says the failure rate is not cause for alarm, but, “If you were a manufacturer, you’d look at that differently.”
ATC officials have reached out to commercial labs to make sure they understand the changes in military testing standards, says Holt. Some labs have started to purchase laser scanners, he says.
For now all the tests are being done at Aberdeen, but during periods of higher demand, the Army is authorized to outsource work to commercial labs that operate the laser scanners. The equipment costs $100,000. “It’s not out of the range of these facilities,” says Holt. “We had an industry day [in June] to show them our work projections and show them our facilities.”
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