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Frangibility
A material is said to be frangible if through deformation it tends to break up into fragments, rather than deforming elastically and retaining its cohesion as a single object. Common crackers are examples of frangible materials, while fresh bread, which deforms plastically, is ''not'' frangible. A structure is frangible if it breaks, distorts, or yields on impact so as to present a minimum hazard. A frangible structure is usually designed to be frangible and to be of minimum mass. Light poles A frangible light pole base is designed to break away when a vehicle strikes it. This lessens the risk of injury to occupants of the vehicle. Frangible supports are also used for airport approach structures. Bullets A frangible bullet is one that is designed to disintegrate into tiny particles upon impact to minimize their penetration for reasons of range safety, to limit environmental impact, or to limit the danger behind the intended target. Examples are the Glaser Safety Slug and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frangible Bullet Stress Test
A material is said to be frangible if through deformation it tends to break up into fragments, rather than deforming elastically and retaining its cohesion as a single object. Common crackers are examples of frangible materials, while fresh bread, which deforms plastically, is ''not'' frangible. A structure is frangible if it breaks, distorts, or yields on impact so as to present a minimum hazard. A frangible structure is usually designed to be frangible and to be of minimum mass. Light poles A frangible light pole base is designed to break away when a vehicle strikes it. This lessens the risk of injury to occupants of the vehicle. Frangible supports are also used for airport approach structures. Bullets A frangible bullet is one that is designed to disintegrate into tiny particles upon impact to minimize their penetration for reasons of range safety, to limit environmental impact, or to limit the danger behind the intended target. Examples are the Glaser Safety Slug and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spall
Spall are fragments of a material that are broken off a larger solid body. It can be produced by a variety of mechanisms, including as a result of projectile impact, corrosion, weathering, cavitation, or excessive rolling pressure (as in a ball bearing). Spalling and spallation both describe the process of surface failure in which spall is shed. The terms ''spall'', ''spalling'', and ''spallation'' have been adopted by particle physicists; in neutron scattering instruments, neutrons are generated by bombarding a uranium (or other) target with a stream of atoms. The neutrons that are ejected from the target are known as "spall". Mechanical spalling Mechanical spalling occurs at high stress contact points, for example, in a ball bearing. Spalling occurs in preference to brinelling where the maximal shear stress occurs not at the surface, but just below, shearing the spall off. One of the simplest forms of mechanical spalling is plate impact, in which two waves of compression ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sacrificial Part
A sacrificial part is a part of a machine or product that is intentionally engineered to fail under excess mechanical stress, electrical stress, or other unexpected and dangerous situations. The sacrificial part is engineered to fail first, thus breaking the serial connection and protecting other parts of the system downstream. Examples Examples of sacrificial parts include: * Electrical fuses * Over-pressure burst disks * Mechanical shear pins * Galvanic anodes * Pyrotechnic fastener * Fusible plug * Some leader lines used in angling Angling is a fishing technique that uses a fish hook or "angle" (from Old English ''angol'') attached to a fishing line to tether individual fish in the mouth. The fishing line is usually manipulated via a fishing rod, although rodless techniqu ... See also * * * Mechanical engineering Safety equipment {{Tech-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friability
Friability ( ), the condition of being friable, describes the tendency of a solid substance to break into smaller pieces under duress or contact, especially by rubbing. The opposite of friable is indurate. Substances that are designated hazardous, such as asbestos or crystalline silica, are often said to be friable if small particles are easily dislodged and become airborne, and hence respirable (able to enter human lungs), thereby posing a health hazard. Tougher substances, such as concrete, may also be mechanically ground down and reduced to finely divided mineral dust. However, such substances are not generally considered friable because of the degree of difficulty involved in breaking the substance's chemical bonds through mechanical means. Some substances, such as polyurethane foams, show an increase in friability with exposure to ultraviolet radiation, as in sunlight. Friable is sometimes used metaphorically to describe "brittle" personalities who can be "rubbed" by seemingl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deformation (engineering)
In engineering, deformation refers to the change in size or shape of an object. ''Displacements'' are the ''absolute'' change in position of a point on the object. Deflection is the relative change in external displacements on an object. Strain is the ''relative'' internal change in shape of an infinitesimally small cube of material and can be expressed as a non-dimensional change in length or angle of distortion of the cube. Strains are related to the forces acting on the cube, which are known as stress, by a stress-strain curve. The relationship between stress and strain is generally linear and reversible up until the yield point and the deformation is elastic. The linear relationship for a material is known as Young's modulus. Above the yield point, some degree of permanent distortion remains after unloading and is termed plastic deformation. The determination of the stress and strain throughout a solid object is given by the field of strength of materials and for a structure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pan Am Flight 845
Pan Am Flight 845 was a Boeing 747-121, registration N747PA, operating as a scheduled international passenger flight between Los Angeles and Tokyo, with an intermediate stop at San Francisco International Airport (ICAO: KSFO). On July 30, 1971, at 15:29 PDT, while it was taking off from San Francisco bound for Tokyo, the aircraft struck approach lighting system structures located past the end of the runway, which seriously injured two passengers and caused significant damage. The crew continued the takeoff, flew out over the ocean and circling while it dumped fuel, and eventually returned for a landing in San Francisco. After coming to a stop, the crew ordered an emergency evacuation during which 27 passengers were injured exiting the aircraft, and 8 of them suffered serious back injuries. The accident was investigated by the NTSB, which determined the probable cause was the pilot's use of incorrect takeoff reference speeds. The NTSB also found various procedural failures ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Security Tape
Security tape (or security label) is a type of adhesive tape used to help reduce shipping losses due to pilfering and theft. It helps reduce tampering or product adulteration. Often it is a pressure sensitive tape or label with special tamper resistant or tamper evident features. It can be used as a ‘’security seal’’ in addition to a container closure or can be used as a security label. They are sometimes used as or with authentication products and can be an anti-pilferage seal. Security tapes and labels are sometimes used in conjunction with security envelopes. Use Security tapes can be used as packaging tapes on small primary packages such as bottles and cartons or on larger shipping containers such as corrugated boxes. They are also used on unit loads or palletized goods. The strength and adhesive bonding are important. Security labels are usually only used for their security features; backing strength is less important but the bonding characteristics are crit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tempered Glass
Tempered or toughened glass is a type of safety glass processed by controlled thermal or chemical treatments to increase its strength compared with normal glass. Tempering puts the outer surfaces into compression and the interior into tension. Such stresses cause the glass, when broken, to shatter into small granular chunks instead of splintering into jagged shards as ordinary annealed glass does. The granular chunks are less likely to cause injury. Tempered glass is used for its safety and strength in a variety of applications, including passenger vehicle windows, shower doors, aquariums, architectural glass doors and tables, refrigerator trays, mobile phone screen protectors, bulletproof glass components, diving masks, and plates and cookware. Properties Tempered glass is about four times stronger than annealed glass. The greater contraction of the inner layer during manufacturing induces compressive stresses in the surface of the glass balanced by tensile stresses in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instrument Landing System
In aviation, the instrument landing system (ILS) is a precision radio navigation system that provides short-range guidance to aircraft to allow them to approach a runway at night or in bad weather. In its original form, it allows an aircraft to approach until it is over the ground, within a of the runway. At that point the runway should be visible to the pilot; if it is not, they perform a missed approach. Bringing the aircraft this close to the runway dramatically increases the range of weather conditions in which a safe landing can be made. Other versions of the system, or "categories", have further reduced the minimum altitudes, runway visual ranges (RVRs), and transmitter and monitoring configurations designed depending on the normal expected weather patterns and airport safety requirements. ILS uses two directional radio signals, the ''localizer'' (108 to 112 MHz frequency), which provides horizontal guidance, and the ''glideslope'' (329.15 to 335 MHz frequency ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ricochet
A ricochet ( ; ) is a rebound, bounce, or skip off a surface, particularly in the case of a projectile. Most ricochets are caused by accident and while the force of the deflection decelerates the projectile, it can still be energetic and almost as dangerous as before the deflection. The possibility of ricochet is one of the reasons for the common firearms safety rule "Never shoot at a flat, hard surface." Ricochets can occur with ''any'' caliber, but short or round ricocheting bullets may not produce the audible whine caused by tumbling irregular shapes. Ricochets are a hazard of shooting because, for as long as they retain sufficient velocity, ricocheting bullets or bullet fragments may cause collateral damage to animals, objects, or even the person who fired the shot. Variables Ricochets occur when a bullet or bullet fragment is deflected by an object rather than penetrating and becoming embedded in that object. Ricochet behavior may vary with bullet shape, bullet material, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GlobalSecurity
GlobalSecurity.org is an American nonpartisan, independent, nonprofit organization that serves as a think tank, and research and consultancy group. Focus The site is focused on national and international security issues; military analysis, systems, and strategies; intelligence matters; and space policy analysis. History It was founded in December 2000 by John Pike, who had worked since 1983 with the Federation of American Scientists, where he directed the space policy, cyberstrategy, military analysis, nuclear resource, and intelligence resource projects. GlobalSecurity.org is headquartered in the Washington, D.C. metropolitan area in Alexandria, Virginia, and Pike remains as its director. The website's target audience includes journalists, policy-makers, scholars, political scientists, military and defense personnel, and the public. It supplies background information and developing news stories, providing online analysis and articles that analyze what are sometimes little-disc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cracker (food)
A cracker is a flat, dry baking, baked food typically made with flour. Flavorings or seasonings, such as salt, herbs, seeds, or cheese, may be added to the dough or sprinkled on top before baking. Crackers are often branded as a nutritious and convenient way to consume a staple food or cereal grain. Crackers can be eaten on their own, but can also accompany other food items such as cheese or meat slices, fruits, Dipping sauce, dips, or soft spreads such as Fruit preserves, jam, butter, peanut butter, pâté, or mousse. Bland or mild crackers are sometimes used as a palate cleanser in food product testing or flavor testing, between samples. Crackers may also be crumbled and added to soup. The modern cracker is somewhat similar to nautical ship's biscuits, military hardtack, wikt:cracknel, chacknels, and sacramental bread. Other early versions of the cracker can be found in ancient flatbreads, such as lavash, pita, matzo, flatbrød, and crisp bread. Asian analogues include papadu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
