Bulletproof room project
No, Your Walls Are Not Bulletproof … But They Can Be
There are a lot of false ideas floating around about what works as cover — in other words, what sort of things will protect you from getting shot. We’ve all seen actors on television turn a table on its side and hide behind it to shoot, or duck behind a corner and see the bullets hit the wall, but not penetrate it. This has left us with a false idea of how well common items will protect us from the damage caused by flying bullets.
Your Home Isn’t Bulletproof?
In reality, there is little in a home that will stop a bullet. Appliances are often made of sheets of steel that are much too thin to stop a bullet, even a smaller caliber bullet like a .22 LR. Furniture is made of materials that don’t stand a chance against a bullet, even if it’s “heavy” furniture. Interior walls aren’t much better. Made of drywall and studs, a typical bullet can pass through several interior walls before losing enough energy to stop.
It is rumored that in the Old West they said that a .44 bullet (supposedly the most common round of the day) would pass through six inches of pine. If you think about it, that’s quite a bit. My personal testing has shown that a 9mm FMJ, which has more penetrating power than just about any round available, will just barely make it through that six inches. But to be honest, I used stacked-up pieces of plywood, which probably was harder to penetrate.
When you compare that to your home, you see that there is little chance of anything in your home coming close to stopping a pistol round, let alone a rifle round that has much more penetrating power.
Some might say, “But the brick of the home would stop bullets!” I used to think that, too. But then I stuck some bricks together and shot at them. Sadly, I found that the only bullet a typical brick will stop is a .22 LR. Everything else, from a .380 on up, busted through the brick. You see, the air holes in the brick weaken it tremendously. If it was solid, it would probably do much better.
Now, to be fair to the brick, let me say that I had stuck them together with construction adhesive and I didn’t have the weight of an entire wall. It is possible that the weight of the wall above the brick that is hit by the bullet would help hold the brick together, reducing the penetrating power of the bullet. But I wouldn’t want to bet my life on it.
Why Bulletproof Walls?
If you’re stuck in your home and have a bad guy outside, how do you fight effectively, without getting shot? Or if you live in a neighborhood where, sadly, there may be drive-by shootings, is there a solution?
There are numerous reasons why you might need bullet resistant walls. You might be interested in an increased security at home. You might need to include bulletproof drywall to protect your business or home. You might even be interested in DIY bullet resistant panels for doomsday or end of the world scenarios.
Commercial businesses and properties in general are often at risk of attack, as targets of robbery or as a potential threat against tenants, personnel and customers.
Walls
Canarmor® together with partnering architect, designing commercial and retail properties, offer bullet-resistant panels/walls. Our bullet resistant walls are capable of mitigating harm caused by bullets from a rifle, handgun or shotgun. In addition to the bullet-resistant capabilities, Canarmor® panels also provide forced entry protection, storm resistance and blast resistance.
Thanks to innovation, blending ballistic protection into architectural millwork is viable. Today, bullet-resistant wall panels are available and easy to install. They look normal while giving us the crucial safety function we all deserve. Canarmor® Walls will keep building’s or room’s visual appeal, moreover, one can never tell that your walls are bulletproof.
Survival Room
In addition to building walls, we also offer Survival Rooms. These are the rooms where you can sleep tight, knowing that not a single bullet will enter your space. Or gain some time until police arrives.
Canarmor Walls are also soundproof, which gives you the unique opportunity to listen to loud music, scream and shout and make as much noise as you like within those walls.
The main idea is to turn one of the rooms in your house into survival room in emergency situations like attacks, storm, fire etc. Hooked-up to all communication devices, room will offer place to hide before the emergency services arrive. The room also protects from #radiation, explosions, electromagnetic waves, it is completely #soundproof, NIJ IV #bulletproof, #waterproof; can be used as #panicroom, #survivalroom, #partyroom, #secretroom, #escaperoom, #bunker, #mancave etc.
With #canarmor you can design the type of survival room you need in any sizes, we will take care of the rest. Special custom designs are also welcome.
Determining the dimensions of essential medical coverage required by military body armour plates utilizing Computed Tomography
Military body armour is designed to prevent the penetration of ballistic projectiles into the most vulnerable structures within the thorax and abdomen. Currently the OSPREY and VIRTUS body armour systems issued to United Kingdom (UK) Armed Forces personnel are provided with a single size front and rear ceramic plate regardless of the individual’s body dimensions. Currently limited information exists to determine whether these plates overprotect some members of the military population, and no method exists to accurately size plates to an individual.
Method
Computed Tomography (CT) scans of 120 male Armed Forces personnel were analyzed to measure the dimensions of internal thoraco-abdominal anatomical structures that had been defined as requiring essential medical coverage. The boundaries of these structures were related to three potential anthropometric landmarks on the skin surface and statistical analysis was undertaken to validate the results.
Results
The range of heights of each individual used in this study was comparable to previous anthropometric surveys, confirming that a representative sample had been used. The vertical dimension of essential medical coverage demonstrated good correlation to torso height (suprasternal notch to iliac crest) but not to stature (r2 = 0.53 versus 0.04). Horizontal coverage did not correlate to either measure of height. Surface landmarks utilized in this study were proven to be reliable surrogate markers for the boundaries of the underlying anatomical structures potentially requiring essential protection by a plate.
Conclusions
Providing a range of plate sizes, particularly multiple heights, should optimize the medical coverage and thus effectiveness of body armour for Armed Forces personnel. The results of this work provide evidence that a single width of plate if chosen correctly will provide the essential medical coverage for the entire military population, whilst recognizing that it still could overprotect the smallest individuals. With regards to anthropometric measurements; it is recommended, based on this work, that torso height is used instead of stature for sizing body armour. Coverage assessments should now be undertaken for side protection as well as for other populations and females, with anthropometric surveys utilizing the three landmarks recommended in this study.
Factors affecting comfort: human physiology and the role of ballistic clothing
Ballistic protection
Ballistic protection involves protection of body and eyes against projectiles of various shapes, sizes, and impact velocities (Adanur, 1995). Such protection is generally required for soldiers, policemen and general security personnel. Historically, ballistic protection devices were made from metals and were too heavy to wear, but textile materials now provide the same level of ballistic protection as metals but have relatively low weight and are therefore comfortable to wear. Most of the casualties during military combat or during unintended explosions are from the flying matter caused by the explosion hitting the body. It is reported that during military combat, only 19% of casualties are caused by bullets, as high as 59% of casualties are caused by fragments, and about 22% are due to other reasons. The number of casualties due to ballistic impact can be reduced 19% by wearing helmets, 40% by wearing armour and 65% by wearing armour with helmet (Scott, 2000). High-performance clothing used for ballistic protection dissipates the energy of the flying particles by stretching and breaking the yarns and transferring the energy from the impact at the crossover points of yarns (Scott, 2000).
The ballistic protection of a material depends on its ability to absorb energy locally and on the efficiency and speed of transferring the absorbed energy (Jacobs and Van Dingenen, 2001). One of the earliest materials used for ballistic protection was woven silk that was later replaced by high-modulus fibres based on aliphatic nylon 6,6 having a high degree of crystallinity and low elongation. Since the 1970s, aromatic polyamide fibres, such as Kevlar® (Du Pont) and Twaron® (Enka) and ultra-high-modulus polyethylene (UHMPE) are being used for ballistic protection (Scott, 2000).
Composite textiles in high-performance apparel
17.7.2.1 Ballistic protection
Ballistic protection concerns apparel, vests, armors, helmets, and structural reinforcement for vehicles as well. The woven, knitted or nonwoven fabrics, laminates, and composites are used for ballistic protection. The type (knife, hand gun, assault rifle bullet, high-velocity bullet) and level of the threat are considered in design and manufacturing of ballistic protective apparel. The structure of armors may include ceramic plates, special fibers/textile structures, laminated/coated textiles, and composites depending on these parameters. In addition, blunt impact protection could be imparted to armors by including shock-absorbing materials.
Different types of body armor used for ballistic protection and different materials and structures used for body armor, the test methods used for the evaluation of ballistic performance, government regulations related to the manufacturing and use of protective clothing, and the methods of testing in several countries of the world have been described (Wang, Kanesalingam, Nayak, & Padhye, 2014).
In terms of textiles, ballistic protection can be divided into two broad categories: soft, “wearable” armor, wherein the ballistic protection is provided by the soft, flexible textile, and soft-rigid armor, wherein ballistic protection is provided by a combination of inflexible armor plates that are integrated into a high-modulus textile. Soft-rigid composite textile systems for ballistics protection typically comprise ceramic armor plates, for example, boron nitride, tungsten carbide, tungsten disulfide, aluminum nitride, and so forth, coated or contained in high-modulus organic polymers, such as para-aramids, for example, Kevlar and Twaron, or UHMW polyolefins, for example, Spectra and Dyneema (https://www.ncjrs.gov/pdffiles1/nij/247281.pdf) (Owens, 2011).
In such systems, rigid plates are designed to intercept an incoming projectile and disperse its kinetic energy over a large area, while the soft textile is used to disperse as much kinetic energy as possible and cause deformation of the round prior to it reaching the ceramic plates (Owens, 2011). Another technology that has demonstrated the ability to serve in an antiballistic capacity is a composite system consisting of a high-performance antiballistic fiber combined with a shear-thickening colloidal dispersion. Shear-thickening fluids or STFs are liquids whose viscosity increases as a function of applied stress. A mixture of cornstarch and water is the classic example of an STF. Researchers at the University of Delaware have produced antiballistic yarns possessing STFs intercalated into the fiber (Owens, 2011) (Wagner & Brady, 2009).
Ballistic tests of these composite fibers show a 250% increase in stopping power of STF-treated Kevlar fibers compared to Kevlar alone. Production of these STF-enhanced textiles for other applications has already begun by Dow Corning under the name Deflexion. Now, consider a merger of M-5 fiber with STF technology and it becomes apparent that soft antiballistic armor will soon be a reality (Owens, 2011). The protective power of typical aramid-based multilayered ballistic fabrics designed to defeat high-velocity ballistic impacts can be improved if wool is incorporated into the weave structure. Ballistic tests have shown that synthetic fabrics blended with wool can at least match the dry or wet ballistic performance of an equivalent pure Kevlar fabric when tested under National Institute of Justice (NIJ) (2014) Ballistic Standard Level III A. The inclusion of the wool can significantly improve the tear strength of pure synthetic ballistic fabrics (Sinnppoo, Arnold, & Padhye, 2010). The use in range of wool fiber and its blends can be increased and further explored for technical textiles applications. Tegris® is a thermoplastic 100% polypropylene composite for hard and soft armor applications, including personal body armor, vehicle armor, blast blankets, and a number of other armor-related applications to counter fragment, projectile, and blast threats (http://millikenmilitary.milliken.com/en-us/technologies/Pages/composites.aspx).
For lightweight stiffness, TYCOR-reinforced core materials are comprised of closed cell foam wrapped in fiberglass. When laid in a mold and infused with resin, TYCOR becomes a stiff, strong material lighter then infused balsa. TYCOR can be used in a variety of applications including bridges, boats, submarine camels, and more (http://millikenmilitary.milliken.com/en-us/products/Pages/impact-resistant-composites.aspx).
The US Army is experimenting with new, advanced composites, to improve vehicle and body armor, providing lighter and more effective protection from different threats, including bullets, fragments, IEDs, and mines. One of the most promising materials is the new high-strength M5 fiber, developed by Akzo Nobel central research labs and currently produced by Magellan Systems International. It has an extraordinary potential for use in armor systems for personnel and vehicles, flame and thermal protection, as well as in high-performance structural composites. Potential Army applications of the fiber include fragmentation vests and helmets, composites for use in conjunction with ceramic materials for small arms protection and structural composites for vehicles and aircraft. It enables the fabrication of advanced lightweight composites into hard and soft ballistic armor. M5 offers significant advantages over both steel and carbon, which is currently used for fabrication of aerospace and automotive structural parts (http://defense-update.com/products/m/m-5-fiber.htm).
M5 fiber is based on the rigid-rod polymer poly{diimidazo pyridinylene (dihydroxy) phenylene}; M5 fiber-based armor has the potential to substantially decrease the weight of body armor while enhancing or maintaining impact performance. Composite fragmentation armor systems were developed using less than optimal quality M5 fiber and tested under ballistic impact; the performance of these armor systems was exceptional. The crystal structure of M5 is different from all other high-strength fibers; the fiber not only features typical covalent bonding in the main chain direction, but it also features a hydrogen bonded network in the lateral dimensions. M5 fibers currently have an average modulus of 310 GPa, (i.e., substantially higher than 95% of the carbon fibers sold), and average tenacities currently higher than aramids (such as Kevlar or Twaron) and on a par with PBO fibers (such as Zylon), at up to 5.8 GPa. Based on these results, it is estimated that fragmentation protective armor systems based on M5 will reduce the areal density of the ballistic component of these systems by approximately 40%–60% over Kevlar KM2 fabric at the same level of protection (Cunniff & Auerbach, http://web.mit.edu/course/3/3.91/www/slides/cunniff.pdf).
The central tasks of ballistic protection are the absorption and the dissipation of energy caused by a ballistic impact. For this reason, bulletproof vests generally consist of a number of layers. Their fabrics or composite layups are made of yarns of high-performance fibers. At the impact of a bullet the material absorbs the kinetic energy—a handgun projectile travels at a speed of 400 m a second—by stretching of fibers and other stiff fibers which disperse the load over a large area throughout the material. This slows the bullet down and finally hinders it from penetrating the body. Body armor designed specifically to defeat rifle fire has to be more rigid, because those projectiles travel at speeds of around 800 m a second. Therefore, besides the layers with fibers, hard materials such as ceramics or metal plates have to be inserted. The protective plates absorb and dissipate this greater kinetic energy upon impact and also the bullet itself gets blunted.
Carbon nanotube fibers woven as a cloth or incorporated into the polymer matrix composite materials are also reported to improve the ballistic performance and enhance stiffness, strength, and toughness against the most aggressive ballistic threats.
DuPont has developed its next generation of bullet-resistant Kevlar fiber that is stronger and lighter than previous versions. Kevlar XP promises to stop 44 Magnum rounds in the first two to three layers of an 11-layer vest, according to DuPont and independent lab tests. While that is impressive, DuPont says it can do this with 10% less weight and 15% less backface deformation which directly translates into less blunt force trauma to vest wearers. While 10% less weight may not sound like much, police officers and soldiers are grateful for a lighter vest, especially when they have to wear tens or even hundreds of pounds of extra gear.
The nature of protective clothing means that there are naturally similarities between different products. For example, there are a number of similarities between bulletproof and stabproof vests, including materials and design. This may seem obvious, but even Turnout Gear shares a number of similarities with bulletproof vests, beyond that both are used to protect an individual. Even their design and development follow similar paths due to the desired end result. Kevlar is not only incredibly strong, but is lightweight and flexible. This is why it is so heavily favored in body armor manufacture. However, aramids are also capable of withstanding extreme temperatures, and will not melt or degrade at temperatures up to 800°F. This means that Kevlar has also found use in Turnout Gear, although aramid manufacturers often look to provide materials with far higher heat resistance, usually at the expense of some ballistic protection. Nevertheless, Kevlar does find uses in Turnout Gear, offering some protection against impacts and blunt trauma. Some manufacturers offer blends of materials, for example, a mixture of Kevlar and Nomex, another aramid material from DuPont that has a far higher resistance to heat. By producing a blend the material can offer the heat resistance needed by firefighters while also decreasing friction and improving co-operation between the layers of Turnout Gear.
Reinforcements and General Theories of Composites
1.5.6.3 Ballistic Composites
Products for ballistic protection can be grouped as flexible products like bomb blankets and bullet resistant vests, and rigid composite products like protective panels and military and police helmets. Over the years various models have been proposed that describe ballistic impact,162 including models for ballistic or blast impact of UHMWPE based composites.163–165 High-performance fibers used in ballistic products are characterized by a low density, high strength, and high energy absorption capability. However, the ballistic performance of a material depends not only on its capability to absorb energy locally, but also on the capability to distribute energy fast and efficiently. Cunniff166 proposed simple dimensionless parameters for the optimization of armor, were tensile strength, elongation at break and sonic velocity in the fiber are the most important parameters. The specific energy absorption capability is related to the specific fiber strength and strain at break:
The sonic velocity is the square root of the specific modulus:
The ballistic potential of various high-performance fibers is compared in Fig. 27, where the sonic velocity (Vs) is plotted against the specific energy absorption (Esp) capability of several polymeric fibers. UHMWPE fibers clearly exhibit a good balance of both these properties (Fig. 28).167
PE fiber-reinforced ballistic products contain either woven fabrics or impregnated and cross-ply unidirectional reinforcement. Commercial ballistic products reinforced with cross-ply fiber laminates include Dyneema UD-HB (Fig. 29) and SpectraShield. Whereas in composites reinforced with glass fibers or aramids mainly toughened thermoset resins are used, ballistic composites reinforced with woven fabrics are often all-PE composites. The composites are produced by stacking layers of UHMWPE fabric and low density PE films. Easy production and post forming in the final shape are distinctive advantages. Laminates consisting of cross-plied unidirectional UHMWPE fibers in an elastomeric matrix like Kraton were initially developed by Allied Signal (SpectraShield)168,169 and later by DSM High Performance Fibers (Dyneema UD-HB) for making composites with a higher ballistic efficiency than possible with fabric reinforced composites.
Cross-plied UD-composites like SpectraShield and Dyneema UD-HB are superior for stopping ballistic projectiles because of the faster distribution of energy as a result of the fully aligned fibers (Fig. 30).
Electronic textiles for military personnel
11.3.3 Comfort
When designing e-textiles for military applications, the comfort of soldiers should never be forgotten. However, the inherent nature of the clothing integrated with electronics to achieve desired levels of protection for soldiers may also affect the degree of comfort. The thickness, type of material used and design aspects of the clothing tend to retain body heat and perspiration inside the garment, which can all lead to heat and moisture build-up and subsequently compromise the body’s ability to maintain thermal balance, resulting in discomfort and fatigue. The maintenance of thermal balance is one of the most important aspects of apparels (Nayak et al., 2009; Das and Alagirusamy, 2010). Almost all the high-performance fibres currently used in military fabrics are synthetic, and have poor heat and moisture management capability. Furthermore, the integration of electronic components and sensors tends to make clothing bulkier and increases the overall weight. In addition, electronic components generate heat. All the above factors can lead to thermal discomfort.
Comfort attributes depend on thermal regulation, physical sensation, water regulation, nature of the material (fibre and finishes), design aspects and the fit of the clothing. Although research has been done to improve the comfort attributes of synthetics, the improvements have not met the high standard of requirements for soldiers’ uniforms and armour. Hence, future research on the development of smart e-textiles for soldiers should focus on the optimisation of comfort, robustness and proper functionalities.
11.3.3.1 Thermal comfort
The overall thickness of fabrics for ballistic protection must be high to achieve the desired level of performance. In turn, the increased bulk and thickness of body armour reduces the level of thermal comfort. However, the performance of these textiles for ballistic protection is still the essential requirement.
11.3.3.2 Tactile comfort
When integrating electronic components, sensors and actuators into military textiles, care should be taken so that these components do not irritate the skin and produce tactile discomfort. This in turn can affect soldiers’ ability to remain focused on their work, or result in rejection of the clothing. Placing the sensors and actuators in appropriate locations can assist in this respect.
The manufacture, properties, and applications of high-strength, high-modulus polyethylene fibers
18.6.1 Ballistic applications
Because of their high energy absorption at break, HMPE fibers are used in applications for civil, law enforcement, and military personnel where low weight needs to be combined with high protection against mechanical threats. The mechanisms of energy absorption at ballistic speeds are important in ballistic protection. The primary factors that determine the weight needed to stop a projectile are the specific energy absorption, determined by the tenacity and elongation, and the sonic velocity of fibers, determined by the specific modulus, indicating the area of the fabric to be involved in stopping the projectile. HMPE fiber has a very high score in these two properties (Fig. 18.30; Jacobs and van Dingenen, 2001).
The combination of high modulus and high tenacity, and the potential to improve substantially upon this, makes the ballistic potential of an HMPE fiber system beyond that of any other high performance fiber (van der Werff and Heisserer, 2016).
18.6.1.1 Woven fabrics
Woven fabrics are traditionally used for ballistic protection in products as fragment-resistant vests, helmets, panels, and spall liners for use in military and civilian vehicles. The fabric can be impregnated or laminated with various matrix systems. The application determines the fabric style, the number of layers, and the type of matrix system.
18.6.1.2 Nonwovens
Needle-felt HMPE fiber nonwoven material is designed primarily to protect against bullet fragments. It is mainly used in bomb blankets, bomb tents, and bomb disposal suits but also in special designed vests for hunters.
18.6.1.3 Unidirectional sheets
Alternating unidirectional layered HMPE constructions (Fig. 18.29) stop bullets much more effectively than woven fabrics. In the unidirectional construction, a larger part of the sheet is involved in the absorption of energy. At ballistic impact of a fabric, the spread of energy in the fibers is hindered by reflections of the shock waves at the crossover points of the yarns.
HMPE fibers are used both for “soft” and “hard” ballistic protection. Soft ballistic protection is used in vests for the police and military, and protects against fragments and handgun ammunition. The unidirectional construction and the high modulus of the HMPE fiber results in less back face deformation by which the body trauma is reduced. In police vests the unidirectional form is used as such or in combinations with woven fabric from low titer HMPE or other fibers. The HMPE fiber unidirectional sheets have excellent chemical resistance and do not require treatment with water-repellent agents as other materials used in bullet-resistant vests. In addition to the ballistic protection, comfort is an important attribute. HMPE fibers result in the lightest, flexible, and most comfortable vests in its class.
Helmets and lightweight panels are hard armor. The low-weight military helmets protect against fragments from bombs and grenades and handgun ammunition while offering maximum comfort. Using UD sheets, helmets can also provide protection against rifle threats. The armor panels can protect against highly penetrating military rifle ammunition and can be incorporated in vests, in civil cars, and lightweight (military) vehicles. Inserts can be molded into complex shapes for accurate and secure fittings, easy to install and remove, and are used mainly by police SWAT teams and military in combat. In military helicopters and civilian aircraft cockpit doors HMPE fiber panels are used to provide ballistic protection from small arms, and in naval ships and patrol boats as main armor material because it is water resistant, lightweight, and strong. The HMPE hard armor insert or vehicle panel can also be combined as a backing material with a steel or ceramic strike face to create superior protection.
Ceramic matrix composites for ballistic protection of vehicles and personnel
7.1 Introduction
Lightweight hybrid composites that can offer substantial ballistic protection to tactical ground vehicles and, in turn, to military personnel are of ever-growing interest to the US military. One of the major requirements for such a ballistic protection technology is the ability to defeat or protect against the 7.62 mm NATO M80 ball round and 7.62 mm NIJ IV or DIN C5-SF AP round threats. It is also an implicit requirement that such a technology be developed without any capital or operational cost penalties; rather, there must be associated gains in operational efficiency and tactical performance during military action. Therefore, there is a need to develop armor systems that are based on high mass efficiency ballistic-shield materials, innovative and functional hybrid designs, and reliable scaleable processing methods.
Conventional armor materials are typically made of steel, aluminum, or other hard metals. Although these metallic materials primarily perform a structural function, they provide reasonably good ballistic protection (Viechnicki et al., 1991; Aghajanian et al., 2001) at appropriate thicknesses (or areal densities). Often, this approach results in parasitic weight, which not only reduces fuel efficiency but also diminishes mobility in action. Recognizing that rapid deployment, enhanced fuel mileage, and reliable ballistic (and blast) protection are the keys to dominating future battles, new and innovative approaches involving lighter materials such as ceramics and polymers have become absolutely essential. Also recognized is the need for ceramic composite armor capable of surviving multiple hits.
Molecular Dynamics (MD) and Coarse Grain Simulation of High Strain-Rate Elastomeric Polymers (HSREP)
5.1.4 Concluding Remarks
Traditionally, the development of advanced blast- and ballistic-protection systems is carried out almost entirely using legacy knowledge and extensive fabrication-and-test trial-and-error approaches. This approach is not only economically unattractive but is often associated with significantly longer lead times. Consequently, this purely empirical approach has gradually become complemented by the appropriate cost and time-efficient computer-aided engineering (CAE) analyses. This trend has been accelerated by the recent developments in the numerical modeling of transient nonlinear dynamics phenomena such as those accompanying blast and ballistic loading conditions. In particular, advances have enabled the coupling between Eulerian solvers (used to model gaseous detonation products and air) and Lagrangian solvers (used to represent solid components of the protection systems, as well as of the projectiles). It is well-established that the utility of the CAE analyses in the development of blast-/ballistic-protective structures is greatly affected by the availability of high-fidelity physically based dynamic material constitutive (continuum) models. The all-atom and coarse-grained results pertaining to the interaction of shock waves with the material microstructure and the resulting changes in the shock wave and the material can be highly beneficial during the construction of such material models [16].
Physical, Mechanical and Ballistic Properties of Kenaf Fiber Reinforced Poly Vinyl Butyral and Its Hybrid Composites
13.4 Ballistic properties of kenaf fibers reinforced poly vinyl butyral composites and its hybrid
The synthetic composite materials play an important part in ballistic protection and provide an excellent solution in terms of strength over weight ratio but it is expensive due to the high demands for its raw materials (carbon, aramid, etc.) in nonarmor application. Although synthetic fibers have an excellent strength that might be able to substitute the traditional metals, the world welcomed the use of natural fibers in composite materials. The main applications of aramid fiber are high tension conveyor belts, ropes, cables, aircrafts, sports equipment, and protective ballistic fabrics (armor). Despite these advantages, the use of aramid fiber reinforced polymer composites has a tendency to decline because of their high initial costs, their petrochemical nature, and their adverse environmental impact (Tudu, 2009).
In the ballistic composite, the matrix restricts lateral motion of the fibers, giving rise to more energy being absorbed by composites leads to break the fiber. Consequently, less moving yarns may create a higher interply friction, and can act as a buffer against impact resulting in improved ballistic performance (Lim et al., 2012). Nevertheless, the composite may be stiffer and limit fiber extension if the level of fiber-matrix adhesion is too high. A stiffer composite cannot absorb more energy or disperse the energy efficiently; failure initiates with cracking of the matrix because of excess stress concentration.
Despite this growing interest in the natural hybrid composite field, only scarce attention has been devoted to the high-velocity impact behavior of these classes of hybrids. Different methods of analysis have been used for ballistic impact performance, depending on the type of response desired for the particular threat designing. Experiments were performed under bullets (National Institute of Justice (NIJ) tests) and fragments (V50 tests) conditions to study the effect of hybridization on the ballistic resistance of hybrid-laminated composites. The methods consist of residual velocity, V50 ballistic limit, penetration depth, and instrumented techniques. For residual velocity testing, the specimen is completely perforated. The general method for characterizing a material’s ballistic limit is to perform a V50 ballistic test, the velocity at which there is an equal probability of a partial (target was not defeated) or a complete perforation (target was defeated) for the given armor and threat. The NIJ methods are used to determine minimum performance requirements for ballistic resistant protective materials levels. It is typically used for residual strength testing in which penetration resistance is not required. According to military specification MIL-STD-662 F, the test consists of taking a certain number of shots where the projectile penetrates the specimen and that same number of shots where no penetration occurs. This type of testing has been widely used by government agencies and armor manufactures for acceptance testing and material performance rating.
The ballistic experiments were conducted in an indoor firing range at the Weapon Technology Laboratory, Science and Technology Research Institute for Defence, Malaysian Ministry of Defence (STRIDE). All armor materials are subjected to standardized test such National Institute of Justice (United States) in order to be certified as safe-worthy armor materials in Malaysia. By using a powder gun, two types of bullets were fired; 9 mm, 8.0 g full metal jacket bullets and. 22 caliber (diameter of 7.62 mm) fragment simulating projectiles. These tests were performed on flat panels with partial lateral support positioned at 5 m forward from the muzzle of the test barrel to produce impacts of 90 degrees obliquity, as illustrated in Fig. 13.7. The targets were rigidly clamped between rectangular steel frames and perpendicular to the line of flight of the bullet at the point of impact. Both two chronographs and Doppler radar antenna combined with a computer were used to measure the projectile velocity; one chronograph is positioned at 2 m in front of the target and another behind it. Projectiles, which pass through the panel, are considered to be a complete penetration, while the others are defined as being partial penetrations, following the United States Department of Justice’s NIJ. The impact striking velocities (Vs) and residual velocity (Vr) of the projectiles were recorded, while the ballistic limit (V50) was calculated. These types of bullets were shot according to the recorded speed in the NIJ standards.
The effects of hybridization on NIJ levels have been studied for high-velocity impacts. The NIJ results show that the H1 and H2 have passed the 3th level (II), resist bullet speed with more than 358 m/second without penetration, as shown in Table 13.4. The positive effect in terms of NIJ levels compared to the kenaf composite shows that hybridization contributes to the same performance in high-impact penetration tests.
Table 13.4. NIJ levels results
Specimen descriptions | Sample code | NIJ standard level | Thickness (mm) |
---|---|---|---|
11 Aramid/8 kenaf | H1 | Passed level II 358±15 (m/s) 3th level | 13.1 |
9 Aramid/10 kenaf | H2 | Passed level II 358±15 (m/s) 3th level | 14.3 |
19 Kenaf | Kf | Passed level I 358±15 (m/s) 2th level | 17 |
The ballistic limit velocity (V50) was estimated using experimental data on the basis of whether the projectile penetrates the hybrid composite completely or partially, as shown in Table 13.5. It is the most common assessment tool to determine the ballistic performance of a material; however, the accuracy of the estimation increases with increasing number of ballistic tests (Boccaccini et al., 2005). Fig. 13.8 shows a plot between the initial velocity and the residual velocity for the hybrid-laminated composites. An increase in initial velocity results in the increase in the residual velocity (which is zero up to certain initial value) for all the hybrids.
Table 13.5. Ballistic resistance results
Specimen descriptions | Sample code | V50 (m/s) | Thickness (mm) |
---|---|---|---|
11 Aramid/8 kenaf | H5 | 496.8 | 13.1 |
9 Aramid/10 kenaf | H6 | 477.5 | 14.3 |
19 Kenaf | Kf | 417.8 | 17 |
Fig. 13.9 shows the ballistic properties of kenaf/aramid hybrid composites in terms of ballistic limit velocity (V50) compared to kenaf/PVB composites. According to two ballistics test NIJ standards, Type II, IIA, III, IIIA, and the V50 requirement of the US military specification, were calculated. Fig. 13.10 shows the ballistic limit (V50)-volume fraction curves of kenaf and its hybrids. The kenaf volume fraction and aramid volume fraction have a significant effect on the ballistic limit velocity.
Rope, cord, twine, and webbing
13.7.1 Diversity and selection
Most of the chapters in this volume relate to specific functions from ballistic protection to transportation. In contrast to this, ropes and cordage are found in a wide variety of human activities from mooring oil rigs to tying up a parcel. Ropes and cords have an amazing diversity of uses as one-dimensional tension textiles. Inevitably, not all have been mentioned. Rescue ropes for many situations, sewing up wounds, ski tow ropes, tethers for space walks, the list could go on and on, and readers will think of others. However, the descriptions of the wide range of applications should provide analogous advice on the ropes and cords that could be used for applications that have not been specifically covered.
The last paragraph of the previous section shows how, even in what seem commonplace activities, it is necessary to understand what is needed to fit the application and to make the right choice of rope. If wrong choices are made, accidents happen. It may be the wrong rope, a manufacturing fault, an installation fault, or a failure to use a rope in a proper way. There may be damage, injuries, or death that can lead to litigation. Experts then have to decide who, if anyone, may be to blame. Some breaks may be inevitable. An example is the Japanese tsunami of 2011. A great many ships broke loose from their moorings and finished up on land. There are probably no ropes that could have withstood this force, certainly none that a shipowner would consider using.
Performance characteristics of technical textiles: Part III: Healthcare and protective textiles
16.3.2 Ballistic protection
Fibrous materials have been widely used for developing products that primarily aim at ballistic protection. Fig. 16.12 illustrates examples of performance characteristics and related attributes for fibrous products used for ballistic protection. The idea is that these products should be able to absorb large amounts of energy due to their high tenacity, high modulus of elasticity, and low density [18–23]. The most common fibrous product used for ballistic protection is bulletproof vests. This product is also one of the oldest components of protection used by human over the years. Indeed, throughout recorded history, humans have used various types of materials as body armor to protect themselves from external objects and injuries in combat situations. The first protective clothing and shields were made from animal skins. With the invention of firearms around 1500, other materials including wood and metal shields were also used for protection. Although these materials were effective in their protective aspects, they were too heavy and impractical for high physical actions, fast movement, and battle maneuvering. This has resulted in the development of softer body armors. One of the first recorded instances of the use of soft body armor was by the medieval Japanese, who used armor manufactured from silk. It was not until the late 19th century that the first use of soft body armor in the United States was recorded. At that time, the military explored the possibility of using soft body armor manufactured from silk. The project even attracted congressional attention after the assassination of President William McKinley in 1901. While the garments were shown to be effective against low-velocity bullets (i.e., traveling at 400 feet per second or less), they did not offer protection against the new generation of handgun ammunition being introduced at that time (ammunition that traveled at velocities of more than 600 feet per second). This deficiency associated with the prohibitive cost of silk made the concept unacceptable.
World War II was a turning point in the development of body armor with the introduction of the “flak jacket” made from ballistic nylon. The flak jacket was very cumbersome and bulky. It provided protection primarily from ammunition fragments but was ineffective against most pistol and rifle threats. By the late 1960s, new fibers were discovered that made their ways to today’s modern generation of body armors. The invention of Kevlar by DuPont in the 1970s was another significant turning point in the development of body armors (e.g., Kevlar 29). Ironically, the fabric was originally intended to replace steel belting in vehicle tires. In 1988, DuPont introduced the second generation of Kevlar fiber, known as Kevlar 129, which offered increased ballistic protection capabilities against high-energy rounds such as the 9-mm FMJ. In 1995, Kevlar Correctional was introduced, which provided puncture-resistant technology to both law-enforcement and correctional officers against puncture-type threats.
The basic idea of body armor is a simple one. It is based on catching bullet that strikes body armor in a “web” of very strong fibrous assembly [22]. This assembly should absorb and disperse the impact energy that is transmitted to the vest from the bullet, causing the bullet to deform or “mushroom.” Additional energy is absorbed by each successive layer of material in the vest, until such time as the bullet is stopped. This principle requires a large area of the garment to be involved in preventing the bullet from penetrating to the body. Unfortunately and despite the great progress of development, no structure exists that will prevent penetration of all ballistic objects, at the same time being wearable and under all situations.
Typical bulletproof vests are made from multiple layers of woven fabric, with the degree of protection is increased as the number of fabric layers increase. These layers are assembled into a “ballistic panel,” which is then inserted into the “carrier,” which is constructed of conventional garment fabrics such as nylon or cotton. The ballistic panel may be permanently sewn into the carrier or may be removable [23]. Although the overall finished product looks relatively simple in construction, the ballistic panel can be very complex. Even the manner in which the ballistic panels are assembled into a single unit can differ from one product to another. In some cases, the multiple layers are bias stitched around the entire edge of the panel; in others, the layers are tack stitched together at several locations. Some manufacturers assemble the fabrics with a number of rows of vertical or horizontal stitching; some may even quilt the entire ballistic panel. No evidence exists that stitching impairs the ballistic-resistant properties of a panel. Instead, stitching tends to improve the overall performance, especially in cases of blunt trauma, depending upon the type of fabric used.
Plain woven fabric is more suitable for body armors. Neoprene coating or resination is also commonly used [18]. Needle-punched nonwoven fabrics are also used for ballistic protection. These are typically made from high-performance polyolefin fibers such as Dyneema polyethylene. The benefits of using nonwoven structures for these applications stem from their ability to provide protection against sharp fragments by absorbing projectile energy by deformation rather than fiber breakage as is the case with woven fabrics. When needle-punched nonwovens are used for ballistic protection, the felt structure should have very low mass per unit area. However, as the mass increases, woven structures become more superior to nonwoven felts [18]. Nonwoven felts should also be designed in such a way that a high degree of entanglement of long staple fibers is achieved at a minimum degree of needling since excessive needling can produce too much fiber alignment through the structure, which aids the projectile penetration.
In situations where high levels of protection (e.g., rifle fire) are required, body armor of either semirigid or rigid construction should be used. These are typically multilayer fibrous systems incorporating hard materials such as ceramics and metals. The heavy weight and high bulkiness of these body armors prevent their use in routine applications (e.g., by uniformed patrol officers or normal military operations) and restrict their use to tactical situations where it is worn externally for short periods of time when confronted with higher-level threats.
The development of more effective body armors is unlikely to cease as a result of the continuing development of weapons of increasing powers. As indicated earlier, the key aspect of development is the fibrous component from which body armors are made. The newest addition to the Kevlar line is Kevlar Protera, which DuPont made available in 1996. This is believed to be a high-performance fabric that allows lighter weight, more flexibility, and greater ballistic protection in a vest design due to the molecular structure of the fiber. Another development is the spectra fiber, manufactured by the former AlliedSignal, which is an ultrahigh-strength polyethylene fiber used to make Spectra Shield composite. This basically 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. According to AlliedSignal, the resulting nonwoven fabric is incredibly strong and 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. Another product, also developed by the former AlliedSignal, uses the Shield Technology process to manufacture a shield composite called Gold Shield. This is made from aramid fibers instead of the Spectra fiber. Gold Shield is typically made in three types: Gold Shield LCR and GoldFlex, which are used in concealable body armor, and Gold Shield PCR, which is used in the manufacture of hard armor, such as plates and helmets.
Akzo Nobel has also developed various forms of its aramid fiber Twaron for body armor. This fiber uses more than 1000 fine spun single filaments that act as an energy sponge, absorbing a bullet’s impact and quickly dissipating its energy through engaged and adjacent fibers. The use of many filaments is believed to disperse an impact more quickly and allow maximum energy absorption at minimum weights while enhancing comfort and flexibility.
Gas Mask Manuals
How to Wear a Gas Mask
A gas mask, also known as an air purifying respirator, filters chemical gases
and particles from the air. If used properly, a gas mask can help protect you
from the effects of breathing air that has been contaminated with gas, vapor, or
particles. Make sure you have the proper filters for your gas mask and that the
mask is tightly adjusted to fit your face. You can keep your gas mask ready for
disasters by storing it properly and making sure your filters are up to date.
Using a Gas Mask
Shave or wax your facial hair. A gas mask needs to fight tightly on your
face. Facial hair like a beard, sideburns, or a moustache can prevent the
mask from sealing properly. Make sure you shave or wax any facial hair
before testing or wearing a gas mask to ensure the gas mask seals correctly.
Remove jewelry and headwear. Jewelry like earrings and headwear like a
hat or scarf can prevent the gas mask from sealing properly. Before putting
on a gas mask, take off any jewelry or headwear that might get in the way of
the seal
Attach the filter according to the manufacturer’s instructions. There
are many different types of gas masks. How and when to secure the mask’s
filter differs by manufacturer. Call or email the manufacturer and ask them
about the proper way to attach the filter and when you should do it.
Use straps to secure the gas mask over your face. The face piece of a
gas mask is secured to the wearer’s head with straps. Place the mask over
your face. Adjust the straps until the gas mask is fitted firmly over your
face. Straps can have a different modifications, but most (if not all) of
them are easy to adjust.
Breathe as you normally would. A gas mask protects you from contaminants
by filtering out chemicals and other dangerous agents. Once you have the gas
mask on, breathe normally. The contaminants will be removed from the air as
it passes through the filter.
Keep the mask on even if you can’t talk through it. You might not be
able to talk while wearing the mask. Some gas masks will have speaking
capabilities, allowing you to talk while wearing the device. Other gas masks
prevent you from talking while you wear the mask. Check with the
manufacturer if you have questions about your gas mask’s speaking
capabilities
Buying and Testing a Gas Mask
Choose the right type of gas mask. A gas mask can protect you from
various contaminants in the atmosphere, depending on the type of
contaminant. Some gas masks protect against biological substances, while
other will protect you from chemical substances. Nowadays some manufacturers
offering a multi-purpose filters. Purchase a gas mask that has been
approved by a reputable agency to protect against specific hazards.
Buy the appropriate filters. A gas mask is only effective if the proper
filter is used. You may need a different filter for each type of threat you
might face, however, some manufacturers offering a multi-purpose filters.
Test the gas mask. In order to make sure the gas mask is working
properly, you will need to test it. If you received your gas mask from your
employer or other organization, they should run a test with you to ensure
the mask works. If you purchased your gas mask as an individual, contact the
manufacturer about how to test your gas mask at home.
- Since every mask is different, you will need to make sure you consult
your employer or the mask’s manufacturer to determine exactly how to
test it.
Keeping your Gas Mask ready for disasters
Store the mask according to the manufacturer’s instructions. It is
important that a gas mask is stored properly. Consult the manufacturer of
your gas mask and ask how the mask should be stored. Try to store the mask
in a sealed box. Place the sealed box in a cool, dry, dark place like a
closet
Keep your filters up to date. Check the expiration dates on your filters
regularly. If a filter has expired, dispose of it according to
manufacturer’s instructions. You should also make sure you are up to date
with the types of filters you might need, depending on the potential threats
in your area
Inspect the mask regularly. You should inspect your gas mask once a
month to make sure the materials have not degraded. Check the seals on the
gas mask and look for cracks or signs of wear. If you notice any cracks in
the gas mask materials, you should have it inspected by a professional
before depending on it during a disaster.
What Do The NIJ Protection Levels Mean?
What Do The NIJ Protection Levels Mean?
Personal protection has always been key for those in battle. Steel, chainmail, and leather armor did the trick back when blades and arrows were the threat, but with firearms and artillery to deal with, tactical vests and armor plates are the go-to body armor.
Not all body armor is created equal though. The threat levels for ballistic vests are set by the NIJ (National Institute of Justice). There are currently five levels in use – Level IIA, II, IIIA, III, and IV – and each covers a different caliber of bullet. We’ll help you understand all the NIJ levels so you can assess which level defeats the range of threats most likely to come your way.
TABLE OF CONTENTS
National Institute of Justice (NIJ) Protection Levels
Is There A Level 5 Body Armor?
Special Level Armor
How Are Stab Proof/Spike Proof Vests Rated?
What Should I Know About NIJ Standards?
NATIONAL INSTITUTE OF JUSTICE (NIJ) PROTECTION LEVELS
This chart gives a detailed rundown of different weapons Levels II to IIIA defend against and other variables (muzzle velocity, etc.). We’ll provide more explanation and context and also include links to featured armor of different levels from our body armor collection.
Keep in mind that each level can protect from its own threat range AND those of the previous levels. So a level IIIA armor protects from the same threats as level II and below.
NIJ LEVEL I BODY ARMOR
The original NIJ Level – now out of commissionThe Level I protection rating was created in the 1970s and is now obsolete. If you come across a Level I vest, consider it either memorabilia or junk.
NIJ LEVEL IIA BODY ARMOR
The current lowest level of protectionLevel IIA armor is the lightest and most flexible armor available today but largely out of date. Usually soft armor, it’s easily concealed beneath clothes.
LEVEL IIA PROTECTS AGAINST:
- .9mm FMJ (Full Metal Jacket) at 1165 feet per second (ft./s)
- .40 S&W (Smith & Wesson) FMJ at 1065 ft./s
NIJ LEVEL II BODY ARMOR
“HANDGUN ARMOR,” DEFEATING UP TO .357 MAGNUM ROUNDS
Level II vests are still relatively light, flexible, and easily discrete under clothes, but can defeat a higher range of ammunition than Level IIA. They also offer more blunt force protection than IIA.
LEVEL II PROTECTS AGAINST:
- all handgun rounds, up to and including .357 magnum jacketed soft point (JSP)
FEATURED LEVEL II ARMOR FROM OUR COLLECTION:
Canarmor’s Lightweight Stab proof/Bulletproof Vest
NIJ LEVEL IIIA BODY ARMOR
Good all-round for concealable, lightweight protectionLevel IIIA is the most common protection level you’ll see when browsing for soft body armor.
Found in everything from ballistic vests to bulletproof backpacks, it’s a bit heavier than Level IIA or II but still largely concealable.
LEVEL IIIA PROTECTS AGAINST:
- 9 mm rounds traveling at speeds of up to 1400 ft./s.
- .44 magnum rounds.
FEATURED LEVEL IIIA ARMOR FROM OUR COLLECTION:
Legacy Tactical Level IIIA Concealable Vest
LEVEL IIIA+
Some suppliers offer level IIIA+ vests that protect against shotgun rounds, 9 mm Civil Defense rounds, and FN 5.7. While such vests aren’t officially certified by the NIJ, it’s becoming a popular option for niche use.
NIJ LEVEL III BODY ARMOR
Rifle-defeating armorLevel III body armor is the first level that protects against rifle rounds. This armor usually consists of hard plates as opposed to soft plates, so it’s not concealable.
Hard armor is also heavier than soft armor, but with that weight comes greater protection.
LEVEL III IS DESIGNED TO HANDLE:
- Six shots from a 7.62×51 NATO round traveling up to 2780 ft./s
FEATURED LEVEL III ARMOR FROM OUR COLLECTION:
Tomahawk, Mohawk and Patriot armours
LEVEL III+ BODY ARMOR
Like Level IIIA+, III+ isn’t an official NIJ rating. However, it’s used by some manufacturers to indicate that this armor has the same protective capacity as Level III but can handle extra threats like M855 “green tip” ammo or M193.
Level III+ is becoming a popular option for those who face additional threats.
NIJ LEVEL IV BODY ARMOR
Top level protectionLevel IV body armor is the highest basic level. It consists of hard plates as opposed to Level IIIA plates and below. Level IV armor achieves this standard by stopping a single bullet as opposed to Level III’s six, so it isn’t always better than a Level III armor.
LEVEL IV IS DESIGNED TO HANDLE:
- One hit from 7.62MM armor piercing rifle (APR) bullet with a velocity of 2880 ft./s.
Featured Level IV armor from our collection:
CANARMOR’s NIJ IV ballistic plates
IS THERE A LEVEL 5 BODY ARMOR?
As of this writing there isn’t, but in the future? Who knows!
SPECIAL LEVEL ARMOR
Special type body armor can go beyond the standard protection rating. Level IIIA+ falls under this classification, for example.
Special type armor usually has very specific protection ratings in terms of caliber and traveling speed of the round.
HOW ARE STAB PROOF/SPIKE PROOF VESTS RATED?
Stab and spike proof vests are designed to fend off slashes or powerful stabs instead of ballistic threats.
The NIJ rates stab / spike proof vests by their ability to resist a certain number of joules of energy behind a blade or spike attack.
- Level 1- 24 joules
- Level 2- 33 joules
- Level 3-43 joules
WHAT SHOULD I KNOW ABOUT NIJ STANDARDS?
The National Institute of Justice (NIJ) currently does testing for five different levels of protection, each designed to resist certain ballistic levels.
The different levels are meant to fit a certain need or situation.
With this knowledge, we hope you can browse body armor collections with more confidence.
Remember, the highest rating possible isn’t necessarily the best choice for you. Consider factors like cost, weight, or comfort of the gear.
Have a question about protection levels? Contact us and our experts will help!