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Kevlar is a heat-resistant and strong synthetic fiber, related to other aramids such as Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, this high-strength material was first used commercially in the early 1970s as a replacement for steel in racing tires. Typically it is spun into ropes or fabric sheets that can be used as such or as an ingredient in composite material components.
Armor-piercing ammunition is a type of projectile designed to penetrate either body armor or vehicle armor.
A ballistic vest or bullet-resistant vest, often called a bulletproof vest, is an item of body armor that helps absorb the impact and reduce or stop penetration to the torso from firearm-fired projectiles and shrapnel from explosions. This armour may come in a soft form, as worn by many police officers, prison guards, security guards and some private citizens, or hard-plate, reinforced vests, allowing for protection against rifle ammunition or explosion shrapnels, which would become relevant for army soldiers, S.W.A.T. teams, H.R.T. agents, and special forces soldiers. Prison guards and police may wear soft vests designed to resist stabbing attack, using metallic or para-aramid components.
Chobham armour is the informal name of a composite armour developed in the 1960s at the British tank research centre on Chobham Common, Surrey. The name has since become the common generic term for composite ceramic vehicle armour. Other names informally given to Chobham armour include "Burlington" and "Dorchester." "Special armour" is a broader informal term referring to any armour arrangement comprising "sandwich" reactive plates, including Chobham armour.
Bulletproof glass is a strong and optically transparent material that is particularly resistant to penetration by projectiles. Like any other material, it isn’t completely impenetrable. It is usually made from a combination of two or more types of glass, one hard and one soft. The softer layer makes the glass more elastic, so it can flex instead of shatter. The index of refraction for both of the glasses used in the bulletproof layers must be almost the same to keep the glass transparent and allow a clear, undistorted view through the glass. Bulletproof glass varies in thickness from 3⁄4 to 3 1⁄2 inches.
Body armor, also known as body armour, personal armor/armour, or a suit/coat of armour, is protective clothing designed to absorb or deflect physical attacks. Historically used to protect military personnel, today it is also used by various types of police, private security guards or bodyguards, and occasionally ordinary civilians. Today there are two main types: regular non-plated body armor for moderate to substantial protection, and hard-plate reinforced body armor for maximum protection, such as used by combat soldiers.
Ultra-high-molecular-weight polyethylene is a subset of the thermoplastic polyethylene. Also known as high-modulus polyethylene, (HMPE), it has extremely long chains, with a molecular mass usually between 3.5 and 7.5 million amu. The longer chain serves to transfer load more effectively to the polymer backbone by strengthening intermolecular interactions. This results in a very tough material, with the highest impact strength of any thermoplastic presently made.
A trauma plate, also known as an armour plate or ballistic plate, is a protective armoured plate inserted into a carrier or bulletproof vest, that can protect by itself, or increase the protection of the vest.
Natural fibers or natural fibres are fibers that are produced by plants, animals, and geological processes. They can be used as a component of composite materials, where the orientation of fibers impacts the properties. Natural fibers can also be matted into sheets to make paper or felt.
In materials science, fracture toughness is the critical stress intensity factor of a sharp crack where propagation of the crack suddenly becomes rapid and unlimited. A component's thickness affects the constraint conditions at the tip of a crack with thin components having plane stress conditions and thick components having plane strain conditions. Plane strain conditions give the lowest fracture toughness value which is a material property. The critical value of stress intensity factor in mode I loading measured under plane strain conditions is known as the plane strain fracture toughness, denoted . When a test fails to meet the thickness and other test requirements that are in place to ensure plane strain conditions, the fracture toughness value produced is given the designation . Fracture toughness is a quantitative way of expressing a material's resistance to crack propagation and standard values for a given material are generally available.
Metakaolin is the anhydrous calcined form of the clay mineral kaolinite. Minerals that are rich in kaolinite are known as china clay or kaolin, traditionally used in the manufacture of porcelain. The particle size of metakaolin is smaller than cement particles, but not as fine as silica fume.
The ballistic limit or limit velocity is the velocity required for a particular projectile to reliably penetrate a particular piece of material. In other words, a given projectile will generally not pierce a given target when the projectile velocity is lower than the ballistic limit. The term ballistic limit is used specifically in the context of armor; limit velocity is used in other contexts.
Ceramic armor is armor used by armored vehicles and in personal armor to resist projectile penetration through high hardness and compressive strength. Ceramics are often used where light weight is important, as they weigh less than metal alloys for a given degree of resistance. The most common materials are alumina, boron carbide, silicon carbide, and titanium diboride.
Niranjan Krishna Naik is an Indian Aerospace Engineer and Professor Emeritus at Indian Institute of Technology Bombay,Mumbai. He is known for his research work on thermomechanical behavior of textile composites and ballistic impact, low velocity impact, fatigue and fracture of composites. His special interest is also on science and technology of aircraft production. Major awards and recognitions conferred to him are: Fellowship of the National Academy of Sciences, India (2004); Fellowship of the Indian National Academy of Engineering (2005); Professor H. H. Mathur Award for "Excellence in Research in Applied Sciences 2006" by IIT Bombay; "Excellence in Aerospace Education Award 2008" by the Aeronautical Society of India; Aerospace Engineering Division Gold Medal of the Institution of Engineers (India) for the year 1992-93 for his research on polymer matrix composites and "Shri Hotchand M. Lala and Shrimati Jamuna H. Lala Excellence in Teaching Award, 2013" by IIT Bombay.
Ceramic matrix composites (CMCs) are a subgroup of composite materials and a subgroup of ceramics. They consist of ceramic fibers embedded in a ceramic matrix. The fibers and the matrix both can consist of any ceramic material, whereby carbon and carbon fibers can also be regarded as a ceramic material.
Carbon fiber reinforced polymer, Carbon fibre reinforced polymer, or carbon fiber reinforced plastic, or carbon fiber reinforced thermoplastic, is an extremely strong and light fiber-reinforced plastic which contains carbon fibers. The spelling 'fibre' is typically used outside the US. CFRPs can be expensive to produce, but are commonly used wherever high strength-to-weight ratio and stiffness (rigidity) are required, such as aerospace, superstructures of ships, automotive, civil engineering, sports equipment, and an increasing number of consumer and technical applications.
Carbon nanotube metal matrix composites (CNT-MMC) are an emerging class of new materials that are being developed to take advantage of the high tensile strength and electrical conductivity of carbon nanotube materials. Critical to the realization of CNT-MMC possessing optimal properties in these areas are the development of synthetic techniques that are (a) economically producible, (b) provide for a homogeneous dispersion of nanotubes in the metallic matrix, and (c) lead to strong interfacial adhesion between the metallic matrix and the carbon nanotubes. Since the development of CNT-MMC is still in the research phase, the current focus is primarily on improving these latter two areas.
A Bouligand structure is a layered and rotated microstructure resembling plywood, which is frequently found in naturally designed materials. It consists of multiple lamellae, or layers, each one composed of aligned fibers. Adjacent lamellae are progressively rotated with respect to their neighbors. This structure enhances the mechanical properties of materials, especially its fracture resistance, and enables strength and in plane isotropy. It is found in various natural structures including the cosmoid scale of the coelacanth, and the dactyl club of the mantis shrimp and many other stomatopods.
Welding of advanced thermoplastic composites is a beneficial method of joining these materials compared to mechanical fastening and adhesive bonding. Mechanical fastening requires intense labor, and creates stress concentrations, while adhesive bonding requires extensive surface preparation, and long curing cycles. Welding these materials is a cost-effective method of joining concerning preparation and execution, and these materials retain their properties upon cooling, so no post processing is necessary. These materials are widely used in the aerospace industry to reduce weight of a part while keeping strength.
References
- 1 2 WJ Cantwell; J Morton (1991). "The impact resistance of composite materials -- a review". Composites. 22 (5): 347–62. doi:10.1016/0010-4361(91)90549-V.
- ↑ AR Boccaccini; S Atiq; DN Boccaccini; I Dlouhy; C Kaya (2005). "Fracture behaviour of mullite fibre reinforced-mullite matrix composites under quasi-static and ballistic impact loading". Composites Science and Technology. 65 (2): 325–333. doi:10.1016/j.compscitech.2004.08.002.
