Body armor

The ordn uses for polypropylene are varied. It is used in the fabrication of personnel body armor (Refs 6 7) in slurry-type expls for the demolition of concrete structures (Ref 11) as a microporous hydrazine-air (cathode) separator in fuel cells (Ref 9) as a propint binder matl, particularly in caseless ammo, (Refs 5 8) and as a candidate to act as a proplnt aging inhibitor for the 155mm RAP round (Ref 10) Refs 1) Beil 1, 196, (82), [167], 677 and (725) 2) A.V. Topchiev V.A. Krentsel,... 

The civilian advances were accompanied, and often led, by advances in military ordnance. Iron and steel became the basis of swords, spears, arrows, guns, cannon, armor, tanks, warships, and more. In fact, the motivation for inventing and developing new hard materials was often the desire for improved military ordnance. This continues with searches for better body armor, and the inverse searches for more penetrating projectiles. 

The hardness of boron carbide (carbon hexaboride) is not well defined because it is made as sintered compacts which have variable densities, compositions, and defect densities. It is very hard (up to 4400kg/mm2), and of relatively low density, so it has been used extensively as body-armor (McColm,... 

CAUTION Sodium nitrotetrazolate dihydrate is an energetic material with sensitivity to various stimuli. Particular care should be taken to not excessively dry the material, as anhydrous NaNT is considerably more sensitive than the dihydrate. While we encountered no issues in the handling of this material, proper protective measures (face shield, ear protection, body armor, Kevlar gloves, and earthened equipment) should be used at all times. 

Kevlar a polymer fiber that is stronger than steel, but very light. It is used to make bullet-proof vests and other body armor. 

Kevlar, a polymer, is a special kind of fiber that is five times stronger than steel, and it is used to make body armor and sports equipment. 

Two general varieties of aromatic nylons are often employed. A less stiff variety is employed when some flexibility is important, whereas a stiffer variety is used for applications where greater strength is required. While good adhesion with the resin is often desired, poor adhesion is sometimes an advantage such as in the construction of body armor where delamination is a useful mode for absorbing an impact. 

One area that illustrates aspects important to energy dissipation is the fabrication of protective armor. Such armor includes helmets, vests, vehicle exteriors and interiors, riot shields, bomb blankets, explosive containment boxes (aircraft cargo), and bus and taxi shields. In each case energy dissipation is a critical element in the desired behavior of the device. To illustrate this let us look at body armor. 

In the future, body armor may be flexible. Experimentation is underway with shear thickening material using polyethylene glycol (PEG) with nanoparticles that remain flexible until rapidly struck such as with a bullet whereupon it acts as a solid protecting the wearer from the major impact. Kevlar is also being employed to protect space craft and space men from discarded space junk and small meteors. Thus, experimentation in body armor is being applied to additional areas where impact protection is essential. 

The BATF has also ruled that since this type of bullet has a steel ball in its nose, it is considered an armor-piercing handgun round and hence, illegal. It is unlikely that this bullet is capable of piercing body armor. 

Similarly, the problem of the human target extends far beyond the consideration of the effect of one round delivered against an enemy soldier. Incapacitation of enemy troops requires wound ballistic studies which include vulnerability of the human body effects of body armor and armament of friendly troops in terms of weight of principal weapon, weight of ammo carried, weapon accuracy, training time required to reach proficiency with the weapon, and logistical requirements... 

In the last 10 years, significant advances in fibrous monolithic ceramics have been achieved. A variety of materials in the form of either oxide or nonoxide ceramic for cell and cell boundary have been investigated [1], As a result of these efforts, FMs are now commercially available from the ACR company [28], These FMs are fabricated by a coextrusion process. In addition, the green fiber composite can then be wound, woven, or braided into the shape of the desired component. The applications of these FMs involve solid hot gas containment tubes, rocket nozzles, body armor plates, and so forth. Such commercialization of FMs itself proves that these ceramic composites are the most promising structural components at elevated temperatures. 

Armor-piercing (AP) ammunition has a projectile or projectile core constructed entirely from a combination of tungsten alloys, steel, iron, brass, bronze, beryllium copper, or depleted uranium. The most effective AP bullets are usually confined to rifle bullets, as velocity and range are important factors in AP requirements. Some revolver and pistol ammunition is described as metal piercing but, although it would be effective against vehicle bodywork and some body armor, it would be ineffective against heavy armor plate. AP bullets are, with very few exceptions, jacketed. 

The rigid, rod-shaped molecules of Kevlar are very crystalline and can be used to form strong, stiff, high-strength fibers. Although this polymer is fairly expensive, it is used in high-tech applications such as bulletproof body armor. 

Kevlar body armor works by catching a bullet in a multilayer web of woven fabrics. Kevlar s extraordinary strength resists tearing and cutting, allowing the stressed fibers to absorb and disperse the impact to other fibers in the fabric. 

There are some techniques that are clearly useful and principles which can be generally applied to such problems. These can probably best be introduced by means of some examples. The first is from our experience in personal protection. The penetration of fabric body armor by a ballistic projectile is clearly a stochastic phenomenon. For any particular vest-projectile combination, there is a span of velocity in which penetrations and nonpenetrations are mixed. The probability of penetration within this zone is influenced by at least the following factors ... 

The second example is from a mixed biological/physical problem. It deals with the probability that blunt trauma to the chest or abdomen would be lethal to man. It has been used to assess the hazard of large ballistic projectiles moving at moderate velocity, the hazard behind body armor which has stopped a handgun bullet, etc. 

Sturdivan, L. M. "Modeling in Blunt Trauma Research", Second Annual Soft Body Armor Symposium, Miami Beach, FL, Sept 1976. 

Many species of plants and animals have toxic chemicals, body armor, and other ingenious defensive adaptations to protect themselves from competitors or predators. 

Both polyethylene and aramid fibers have increasing applications in a variety of armor products. Body armor is a high performance system for protection against rifle bullets. Armor containing these fibers together with a polymeric matrix in the form a composite can provide ballistic protection as well as structural... 

Figure 4.28 Spectra Shield (a product of AlliedSignal) is a body armor that is made by means of woven fabric of Spectra polyethylene fiber. This figure shows a schematic of cross-plied (0°/90°) Spectra fibers in a resin matrix.

Spectra Shield is a product of AlliedSignal that is made by means of a woven fabric of Spectra polyethylene fiber. Figure 4.28 shows a schematic of cross-plied (0°/90°) Spectra fibers in a resin matrix. Helmets, hard armor for vehicles, and soft body armor are shown in Fig. 4.29. The helmet manufacture involves a special version of Spectra Shield, a special shell design, and a three-way adjustable liner of shock absorbing foam padding. These helmets were used by the UN peacekeeping troops from France in 1993 and were introduced to police forces in the US and Europe. A soft body armor of polyethylene fiber consists of five Spectra Shield plies that slide into the pockets in the body armor. 

Kevlar 29 and versions thereof (K 129 and Kl j.) are also used extensively in lightweight body armor as well as composite liners (with vinylester, polyester or epoxy as the matrix). A quick look at the properties of different Kevlar aramid fibers in Table 4.2 shows why K29 is better than K49 for lightweight body armor applications. K29 has a higher strain to failure than K49. That means that the total work of fracture, i.e. the area under the stress-strain curve, is larger for K29 than K49. Hence, the energy absorbed in the fracture process is higher for K29... 

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