Body Armor 101
When a bullet strikes body armor, it's caught in a "web" of fibers. These fibers absorb and disperse the impact energy that is transmitted to the vest from the bullet.
Because the fibers work together both in the individual layer and with other layers of material in the vest, a large area of the garment becomes involved in preventing the bullet from penetrating. This also helps in dissipating the forces that can cause non-penetrating injuries (commonly referred to as "blunt trauma") to internal organs.
Methods of Construction
Typically, concealable body armor is constructed of multiple layers of ballistic fabric or other ballistic-resistant materials, assembled into the "ballistic panel." The ballistic panel is then inserted into the "carrier," which is constructed of fabrics such as nylon or cotton. The ballistic panel may be permanently sewn into the carrier or may be removable.
Ballistic fabric is available from a number of manufacturers in various styles and compositions, each type having unique ballistic-resistant properties. The location and number of layers of each style within the multiple-layer ballistic panel influence the overall ballistic performance of the panel.
Several manufacturers have been involved in developing and refining materials used in body armor.
DuPont has developed law enforcement protection products for more than 25 years. Its Kevlar brand fiber, first developed in 1965, was the first material identified for use in the modern generation of concealable body armor. Kevlar is a manmade organic fiber, with a combination of properties allowing for high strength with low weight, high chemical resistance, and high cut resistance. Kevlar is also flame-resistant and does not melt, soften, or flow.
Kevlar 29, introduced in the early 1970s, was the first generation of bullet-resistant fibers developed by DuPont and helped to make the production of flexible, concealable body armor practical for the first time. In 1988, DuPont introduced the second generation of Kevlar fiber, known as Kevlar 129. According to DuPont, this fabric offered increased ballistic protection capabilities against high-energy rounds such as the 9mm FMJ. In 1995, Kevlar Correctional was introduced, which provides puncture-resistant technology to both law enforcement and correctional officers against puncture-type threats.
Spectra fiber, manufactured by AlliedSignal (now Honeywell), is an ultra-high-strength polyethylene fiber. Ultra-high molecular weight polyethylene is dissolved in a solvent and spun through a series of small holes, called spinnerets. This solution is solidified by cooling, and the cooled fiber has a gel-like appearance. The Spectra fiber is then used to make Spectra Shield composite. A layer of Spectra Shield composite consists of two unidirectional layers of Spectra fiber, arranged to cross each other at 0- and 90-degree angles and held in place by a flexible resin. Both the fiber and resin layers are sealed between two thin sheets of polyethylene film, which is similar in appearance to plastic food wrap. The resulting non-woven fabric is incredibly strong, lightweight and has excellent ballistic protection capabilities. Spectra Shield is made in a variety of styles for use in both concealable and hard armor applications.
Honeywell also uses the shield technology process to manufacture another type of shield composite called GoldFlex. GoldFlex is manufactured using aramid fibers instead of the Spectra fiber.
Another manufacturer, Akzo Nobel, has developed various forms of its aramid fiber TWARON® for body armor. According to Akzo Nobel, this fiber uses 1,000 or more finely-spun single filaments that act as an energy sponge, absorbing a bullet's impact and quickly dissipating its energy through engaged and adjacent fibers. Because more filaments are used, the impact is dispersed more quickly. Akzo claims their patented microfilament technology allows maximum energy absorption at minimum weights while enhancing comfort and flexibility.
Another fiber used to manufacture body armor is Dyneema. Originated in the Netherlands, Dyneema has an extremely high strength-to-weight ratio (a 1-mm-diameter rope of Dyneema can bear up to a 240-kg load), and has high energy absorption characteristics.
Body Armor Facts
- Studies on officer safety suggest that 42% of officer deaths by firearms may have been prevented if the officer had been wearing concealable body armor.
- Studies also show that of those whose lives could have been saved, 94% needed torso protection from rounds delivered by low- to medium-energy handguns and .22 rimfire rifles and shotguns.
- According to a 1997 Bureau of Justice Statistics survey of 700 state and local law enforcement agencies with 100 or more officers, approximately 40% of sheriff's and municipal police departments, and 25% of state and country police departments require all field officers to wear body armor, compared to slightly less than 30% in the same survey conducted in 1993.
- From 1973 to 2000, a total of 2,500 "saves" have been attributed to the use of body armor.
The top five threats regularly faced by police officers are:
- Blunt trauma
- Hypodermic needles
- Pointed and handmade weapons
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