Q & A with George C. Tillery
Office Director, Office of Science
National Institute of Justice
Office of Justice Programs
U.S. Department of Justice
Kevlar has been the standard for body armor since 1970, is that correct? Is it also correct that Kevlar, in varying compositions, is also used to construct bullet-resistant vehicle panels, bomb blankets and flak jackets used by law enforcement officials, firefighters and military personnel?
Body armor systems (sometimes called “bulletproof vests” although there is no such thing as a bulletproof vest) may include different materials. It is the model and not the material that is tested and deemed compliant. That said, Kevlar is among the most widely used ballistic materials in body armor.
The soft (or concealable) body armor used by police departments today grew out of NIJ-funded research into the potential for DuPont’s Kevlar to be used in body armor. Lester Shubin, who served as NIJ Technology Assessment Program Manager from 1971 to 1991, suspected that it might have the potential to improve personal armor. He and Nicholas Montanarelli, a researcher working for the U.S. Army, took a piece of Kevlar to a gun range, folded it over a couple of times, and shot at it. The bullets did not go through and the research program was initiated.
During the following five years, from 1971 to 1976, NIJ invested more than $3 million to the development of body armor. The research and development program was a team effort involving several of the most innovative and technologically advanced private and government organizations in the country. U.S. Army research agencies continued to play a vital role including Edgewood Arsenal, Aberdeen Proving Grounds, and Natick Laboratories.
The final phase of this program involved operational evaluation. An initial test in three cities determined that the prototype vest was wearable, it did not cause undue stress, or pressure on the torso, and it did not prevent the normal body movement necessary for police work. In 1975, an extensive field test of the new Kevlar body armor was conducted, with 15 urban police departments cooperating. Each department served a population larger than 250,000, and each had experienced officer assault rates higher than the national average. The tests involved 5,000 garments, including 800 purchased from commercial sources.
Ballistic resistant materials or composite material systems, including Kevlar, are used for a number of different ballistic protection applications, for example on the U.S. Army’s MRAP and other combat vehicle systems.
To take advantage of federal funding that is available to law enforcement agencies offset the cost of bullet-resistant body armor, the agencies must have a mandatory wear policy in place. Is choosing from the NIJ list of approved armor also a requirement?
To receive funding through the Bulletproof Vest Partnership (BVP) grant program, an agency must have a mandatory wear policy in place and can only use grant funds to purchase vests that are on the compliant product list for the current NIJ Standard. See www.ojp.usdoj.gov/bvpbasi/
In what way is body armor currently being improved? Could you tell me a little about the improvements that NIJ testers have seen recently, and what future improvements are currently being researched?
Concurrent with its development of body armor, NIJ developed a performance standard for body armor and implemented a testing program to help ensure that the body armor sold to criminal justice agencies was safe and effective. The body armor standard has evolved. Each subsequent version incorporates new research and understanding of body armor performance. The latest version of the standard NIJ0101-06 was published in 2008.
That standard incorporates significantly more stringent testing requirements that prior standards. Among other things, it includes a conditioning protocol intended to provide some indication of an armor’s ability to maintain ballistic performance after being exposed to conditions of heat, moisture and mechanical wear.
In order to meet those more stringent requirements and still provide a body armor that is not too stiff and heavy to wear, manufacturers have moved more to armor systems incorporating heterogeneous as opposed to homogeneous materials, using multiple different types of ballistic fabrics in their construction. They have also innovated in their weaving and stitching techniques. As a result, while we saw an initial increase in the weight and stiffness of armor submitted for testing after the introduction of the new NIJ standard, today we are seeing systems comparable to the older systems with regard to comfort but able to meet the more stringent requirements of the current NIJ standard.
Materials research both within and outside of government, as well as here and overseas, continue to find improved ballistic materials that are lighter and stronger. One example of this is the work being undertaken in the Institute of Soldier Nanotechnologies at the Massachusetts Institute of Technology looking at polyurethane materials (web.mit.edu/isn/) that have potential application to body armor. Today, the ballistic-resistant fabrics used in body armor are typically manufactured from para-aramid or polyethylene materials. Kevlar is a para-aramid fiber.
NIJ funded research is primarily focused on improving body armor design for increased protection and wearability. For example, we funded work at Cornell University to develop a computer aided design tool that would allow manufacturers to optimize the integration of the different layers of ballistic materials in their armors. We funded Wayne State University and Mississippi State University to look at how respectively stab-resistant and ballistic-resistant body armor designs might be improved to reduce even further the likelihood of injury through increased coverage of the body while at the same time allowing an officer to retain the requisite degree of mobility to do their jobs.
We are also funding Wayne State University to do an assessment of the actual impact of wearing body armor on core body temperature. Officers wearing body armor report that it can be hot and uncomfortable. We do not know how much real impact wearing body armor has on body temperature.
We have contributed funding to various materials research efforts including the U.S. Army’s work in the area of liquid armor. Liquid armor involves infusing the material in a body armor vest with a liquid, in the case of the Army’s work polyethylene glycol, in which are suspended hard particles, in this case nanoparticles of silica, creating what is called a shear thickening fluid. Under normal conditions, the liquid in the body armor would remain fluid and the body armor flexible. When subjected to the shock of the impact of a bullet however, the hard particles in the STF in that portion of the body armor subjected to the shock should cause the armor to harden. When the shock dissipates, the armor would return to its flexible state.
The NIJ began meeting in July 2012 to revise the 0101.06 standard. When is the update likely to be completed?
The review of the NIJ Ballistic Armor Standard 0101.06 was initiated in July of this year. The revision will take a fresh look at all aspects of the standard to ensure that it continues to reflect the needs of public safety personnel and yet still allows for innovation in design and construction. Although the scope of changes or amendments is not limited, it is anticipated that this review of the standard will take approximately 24-36 months to fully complete and publish.
What is the potential for nanotechnology to be incorporated into the construction of bullet-resistant body armor?
As can be seen from the preceding discussion, nanotechnology seems to offer the potential for lighter weight, stronger body armor. The potential of this technology is just starting to be explored. It will take time before we know if that potential is born out.
In what other new ways might vests and body armor function in the future?
We expect that the research and development efforts undertaken by government and industry will result in body armor offering improved comfort and fit, while at the same time offering increased protection. That is where our research is aimed.