U.S. Army Natick Researchers Test Soft Armor
A Soft Armor Flexibility Test Apparatus measures armor sample stiffness by plunging it through an 8-inch diameter hole with a 2-inch depth. The new test is operationally relevant and is based on Soldier input regarding comfort and range of motion.|Photo by Vernon Bentz, Aberdeen Test Support Services

Natick Researchers Test Soft Armor, Eyewear For Soldiers

Researchers at the Natick Soldier Research, Development and Engineering Center have found innovative ways to test soft-body armor and protective eyewear.

The following is a release from Jane Benson, NSRDEC Public Affairs:

Researchers at the Natick Soldier Research, Development and Engineering Center, or NSRDEC, have devised new, more operationally relevant ways to evaluate protective eyewear and soft-body armor. These new test methods and apparatus are transitioning to the Aberdeen Test Center, or ATC, and will be incorporated into standardized test operating procedures.

The quick transition to ATC has been enabled by the Science and Technology, or S&T, Objective, or STO, Force Protection Soldier and Small Unit program, formerly TeCD 1b, which focuses on aligning and transitioning science and technology projects to programs of record and various customers.

“STO Force Protection: Soldier and Small Unit comprises 77 projects that are delivering knowledge products, materiel, and test methods – all aimed at understanding and increasing Soldier performance and protection in an operationally relevant environment,” said Jaclyn Fontecchio, STO lead, NSRDEC Warfighter Directorate. “New and relevant test methods are critical to the ability to accurately assess products or systems during their S&T development. As new products emerge through research and development, the use of standard test methods, as is or modified, are not always applicable particularly when dealing with revolutionary or novel products and materials. In many cases, new test methods are required to measure parameters of interest and require an upfront investment. Failure to do so can lead to non-conforming products, shortened product service life, and increased testing costs.”

Natick’s new test methods for protective eyewear and soft-armor protection were needed to evaluate evolving, state-of-the-art protection and new materials/designs, in situations where previous methods were incapable of testing the new materials/designs accurately.

The new test methods include a soft-armor flexibility test, a soft-armor durability test, an eyewear abrasion test, and an eyewear anti-fog test. The new NSRDEC-developed tests are consistent, accurate, reliable, repeatable, and most important, operationally relevant, to ensure that equipment better meets the needs of Soldiers.

SOFT ARMOR TESTING

Previous test methods, which existed for evaluating soft-armor flexibility and durability were written based on woven fabric constructions. These methods were inapplicable to new, higher-performance materials, which were not made of woven construction.

NSRDEC developed a flexibility test for soft armor, which consists of a spherical bend procedure that characterizes the flexibility of multilayer, soft armor ballistic panels.

“Previous soft-armor tests didn’t really translate to someone wearing it in a real environment,” said Robert DiLalla, ballistic and blast thrust area manager. “There was no means to say, was this too hard or too soft? So, we came up with a study that took soft armor panels that were comprised of materials of varying stiffness and put them on Soldiers and had them do a set series of tasks. We asked them how the overall comfort was and took goniometer and reach measurements. We then developed a method by which we could take a sample of that soft armor, plunge it through an eight-inch-diameter hole, and we measured how much force it took to plunge it two inches through. We took all that data of all those designs and compared it to the human-factors assessment. And believe it or not, as you got panels that took more force to plunge, you could see that the Soldiers would say it was too stiff or prohibited range of motion. We found the threshold where Soldiers didn’t like it. We also found a lower threshold where they started to say that it was too soft.”

Thus, the new test methods are a standardized way to evaluate soft armor based on direct Soldier input.

“It is very simple, reliable and repeatable,” DiLalla said. “The apparatus provides an accurate way to test current armor and future designs. The reason that this test is better is that we can actually test a system level, multi-layered system unlike the previous method of measuring the fabric stiffness of a single ply. We wanted to come up with a method that was operationally relevant and that reflected what the Soldiers would think, and at the same time not prohibit new materials/constructions from being used.”

The second new test method measures wear durability with an apparatus that subjects an armor sample to load conditions that replicate physical movements used frequently by warfighters – including squatting, bending and twisting – in a single mechanical stroke.

“In this case when we say durability, we are trying to predict wear life or say that the system will at least last for some period of time. If Soldiers are in theater and wear this every day for a year – will the protection hold up to wear over 12 months? We don’t want a system that will degrade in performance from normal, expected field use. We developed a test method to measure that. We came up with an apparatus that can mechanically work an armor sample in one stroke, and it’s repeatable. Previously, there was no test method available to show how long the ballistic protection would last with typical use.”

PROTECTING EYEWEAR TESTING

Previous testing methods for eye protection, including goggles and spectacles, did not adequately test for real-world conditions, including the desert conditions that have been prevalent in many Soldier operations.

“Our eyewear must be scratch resistant, fog resistant, and protect from dust and sand infiltration,” said Michelle Markey, NSRDEC science and technology researcher. “This can be accomplished through design and specialty coatings. More ventilation can mean less fog, for example, but it can also mean more dust and sand gets in. It’s a challenging balance that continuously needs to be looked at.”

Previously, there wasn’t a very reliable, effective test method for the laboratory. So, researchers had to rely on user field test data, which is time consuming and expensive. NSRDEC developed a new fog test and apparatus that measures anti-fog performance and provides quantifiable measurements that apply to real scenarios.

“Instead of having to test products in the field or a large chamber, we can now do it at a laboratory scale,” Markey said.

Eyewear for Soldiers also needs to work, as part of a system and in conjunction with a helmet, which made private industry test methods inapplicable.

“Wearing eyewear with a helmet can affect air flow,” Markey said. “The existing test methods didn’t account for design, style, how it is worn, and the various environmental conditions the eyewear is used in. So, Natick came up with a test methodology to look at all these different considerations.

“A heated moisture bath in the head form is used to simulate heat and moisture from the eyes. Mounting on a head form also allows the space factor between the eyewear and the head to be considered, as well as the effect of other equipment, such as helmets. The environment is also a factor. Is it cold? Is it warm? What is the relative humidity and what effect does it have? The test apparatus addresses all of this, and is enclosed in a chamber, basically creating a miniature controlled environment for consistent test conditions.”
Service

This type of testing will improve Soldier safety because Service members will be more likely to keep their protective goggles and spectacles on if they do not have problems with fogging.

NSRDEC also developed a new standard test method for abrasion resistance. The method incorporates the use of rapidly blowing sand to replicate real-world conditions. None of the previous methods could accurately replicate this type of damage. In fact, eyewear that performed well under previous methods sometimes performed poorly when exposed to the blowing sand test mechanism.

“Abrasion resistance is always a key concern with eye protection,” Markey said. “It’s a challenge because of the nature of the impact-resistant material we use. It is soft and has to be coated to keep it from scratching. The durability of those coatings must be tested, ideally with something similar to what is experienced in the field. In a desert environment, blowing sand can be quite abrasive.”

CONCLUSION

“People tend to focus on just the products, but they don’t realize that behind the scenes we are working diligently to develop new methods to better assess the performance of these products,” DiLalla said. “In many cases, old-test methods can’t be applied to the new products. So, we need to be the lead, not only in developing these new products, but in developing operationally relevant methods to assess them.

“TECD Force Protection Soldier and Small Unit has been committed not only to developing new material solutions and knowledge products, but also to the development of improved test methods, which is one part of providing better capabilities to the Soldier. The program is set to wrap up at the end of FY2016 with numerous products transitioning to multiple stakeholders.”

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