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Adiabatic Shear Band
In physics, mechanics and engineering, an adiabatic shear band is one of the many mechanisms of failure that occur in metals and other materials that are deformed at a high rate in processes such as metal forming, machining and ballistic impact. Adiabatic shear bands are usually very narrow bands, typically 5-500 μm wide and consisting of highly sheared material. '' Adiabatic'' is a thermodynamic term meaning an absence of heat transfer – the heat produced is retained in the zone where it is created. (The opposite extreme, where all heat that is produced is conducted away, is ''isothermal''.) Deformation It is necessary to include some basics of plastic deformation to understand the link between heat produced and the plastic work done. If we carry out a compression test on a cylindrical specimen to, say, 50% of its original height, the stress of the work material will increase usually significantly with reduction. This is called ‘work hardening’. During work hardeni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physics
Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular succession of events." It is one of the most fundamental scientific disciplines. "Physics is one of the most fundamental of the sciences. Scientists of all disciplines use the ideas of physics, including chemists who study the structure of molecules, paleontologists who try to reconstruct how dinosaurs walked, and climatologists who study how human activities affect the atmosphere and oceans. Physics is also the foundation of all engineering and technology. No engineer could design a flat-screen TV, an interplanetary spacecraft, or even a better mousetrap without first understanding the basic laws of physics. (...) You will come to see physics as a towering achievement of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cylindrical
A cylinder () has traditionally been a Solid geometry, three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a Prism (geometry), prism with a circle as its base. A cylinder may also be defined as an infinite set, infinite curvilinear surface (mathematics), surface in various modern branches of geometry and topology. The shift in the basic meaning—solid versus surface (as in a solid ball (mathematics), ball versus sphere surface)—has created some ambiguity with terminology. The two concepts may be distinguished by referring to solid cylinders and cylindrical surfaces. In the literature the unadorned term "cylinder" could refer to either of these or to an even more specialized object, the ''right circular cylinder''. Types The definitions and results in this section are taken from the 1913 text ''Plane and Solid Geometry'' by George A. Wentworth and David Eugene Smith . A ' is a Surface (mathematics), surface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precipitation Hardening
Precipitation hardening, also called age hardening or particle hardening, is a heat treatment technique used to increase the yield strength of malleable materials, including most structural alloys of aluminium, magnesium, nickel, titanium, and some steels, stainless steels, and duplex stainless steel. In superalloys, it is known to cause yield strength anomaly providing excellent high-temperature strength. Precipitation hardening relies on changes in solid solubility with temperature to produce fine particles of an impurity phase, which impede the movement of dislocations, or defects in a crystal's lattice. Since dislocations are often the dominant carriers of plasticity, this serves to harden the material. The impurities play the same role as the particle substances in particle-reinforced composite materials. Just as the formation of ice in air can produce clouds, snow, or hail, depending upon the thermal history of a given portion of the atmosphere, precipitation in solids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-entropy Alloy
High-entropy alloys (HEAs) are alloys that are formed by mixing equal or relatively large proportions of (usually) five or more elements. Prior to the synthesis of these substances, typical metal alloys comprised one or two major components with smaller amounts of other elements. For example, additional elements can be added to iron to improve its properties, thereby creating an iron-based alloy, but typically in fairly low proportions, such as the proportions of carbon, manganese, and others in various steels. Hence, high-entropy alloys are a novel class of materials. The term "high-entropy alloys" was coined by Taiwanese scientist Jien-Wei Yeh because the entropy increase of mixing is substantially higher when there is a larger number of elements in the mix, and their proportions are more nearly equal. Some alternative names, such as multi-component alloys, compositionally complex alloys and multi-principal-element alloys are also suggested by other researchers. Compositionall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Depleted Uranium
Depleted uranium (DU), also referred to in the past as Q-metal, depletalloy, or D-38, is uranium with a lower content of the fissile isotope Uranium-235, 235U than natural uranium. The less radioactive and non-fissile Uranium-238, 238U is the main component of depleted uranium. Uranium is notable for the extremely high density of its metallic form: at , uranium is more dense than lead. Depleted uranium, which has about the same density as natural uranium, is used when this high density is desirable but the higher radioactivity of natural uranium is not. Civilian uses include counterweights in aircraft, radiation shielding in medical radiation therapy, research and industrial radiography equipment, and containers for transporting radioactive materials. Military uses include Vehicle armour, armor plating and Armor-piercing shot and shell, armor-piercing projectiles. The use of DU in munitions is controversial because of concerns about potential long-term health effects. Normal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinetic Energy Penetrator
A kinetic energy penetrator (KEP), also known as long-rod penetrator (LRP), is a type of ammunition designed to penetrate vehicle armour using a flechette-like, high- sectional density projectile. Like a bullet or kinetic energy weapon, this type of ammunition does not contain explosive payloads and uses purely kinetic energy to penetrate the target. Modern KEP munitions are typically of the armour-piercing fin-stabilized discarding sabot (APFSDS) type. History Early cannons fired kinetic energy ammunition, initially consisting of heavy balls of worked stone and later of dense metals. From the beginning, combining high muzzle energy with projectile weight and hardness have been the foremost factors in the design of such weapons. Similarly, the foremost purpose of such weapons has generally been to defeat protective shells of armored vehicles or other defensive structures, whether it is stone walls, sailship timbers, or modern tank armour. Kinetic energy ammunition, in its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tungsten
Tungsten (also called wolfram) is a chemical element; it has symbol W and atomic number 74. It is a metal found naturally on Earth almost exclusively in compounds with other elements. It was identified as a distinct element in 1781 and first isolated as a metal in 1783. Its important ores include scheelite and wolframite, the latter lending the element its alternative name. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all known elements, melting at . It also has the highest boiling point, at . Its density is 19.254 g/cm3, comparable with that of uranium and gold, and much higher (about 1.7 times) than that of lead. Polycrystalline tungsten is an intrinsically brittle and hard material (under standard conditions, when uncombined), making it difficult to work into metal. However, pure single-crystalline tungsten is more ductile and can be cut with a hard-steel hacksaw. Tungsten occurs in many alloys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platinum
Platinum is a chemical element; it has Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name originates from Spanish language, Spanish , a diminutive of "silver". Platinum is a member of the platinum group of elements and group 10 element, group 10 of the periodic table of elements. It has six naturally occurring isotopes. It is one of the Abundance of elements in Earth's crust, rarer elements in Earth's crust, with an average abundance of approximately 5 microgram, μg/kg, making platinum about 30 times rarer than gold. It occurs in some nickel and copper ores along with some Native element mineral, native deposits, with 90% of current production from deposits across Russia's Ural Mountains, Colombia, the Sudbury Basin, Sudbury basin of Canada, and a large reserve in South Africa. Because of its scarcity in Earth's crust, only a f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henri Tresca
Henri Édouard Tresca (12 October 1814 – 21 June 1885) was a French mechanical engineer, and a professor at the Conservatoire National des Arts et Métiers in Paris. Work on plasticity He is the father of the field of plasticity, or non-recoverable deformations, which he explored in an extensive series of experiments begun in 1864. He stated one of the first criterion of material failure, that now bears his name. The criterion specifies that a material would flow plastically if \ \sigma_=\sigma_1-\sigma_3 > \sigma_ Tresca's criterion is one of two main failure criteria used today for ductile materials. The second important criterion is due to Richard von Mises. See comparison on the image left: Design of the International Prototype Metre Tresca was also among the designers of the prototype metre bar that served as the first standard of length for the metric system. After the Convention of the Metre had been signed in 1875, the International Bureau of Weights and Mea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forging
Forging is a manufacturing process involving the shaping of metal using localized compression (physics), compressive forces. The blows are delivered with a hammer (often a power hammer) or a die (manufacturing), die. Forging is often classified according to the temperature at which it is performed: cold forging (a type of cold working), warm forging, or hot forging (a type of hot working). For the latter two, the metal is heated, usually in a forge. Forged parts can range in weight from less than a kilogram to hundreds of metric tons.Degarmo, p. 389 Forging has been done by metalsmith, smiths for millennia; the traditional products were kitchenware, household hardware, hardware, hand tools, edged weapons, cymbals, and jewellery. Since the Industrial Revolution, forged parts are widely used in mechanism (engineering), mechanisms and machines wherever a component requires high strength of materials, strength; such forgings usually require further processing (such as machining) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamics (mechanics)
In physics, dynamics or classical dynamics is the study of forces and their effect on motion. It is a branch of classical mechanics, along with ''statics'' and ''kinematics''. The ''fundamental principle of dynamics'' is linked to Newton's second law. Subdivisions Rigid bodies Fluids Applications Classical dynamics finds many applications: * ''Aerodynamics'', the study of the motion of air * '' Brownian dynamics'', the occurrence of Langevin dynamics in the motion of particles in solution * '' File dynamics'', stochastic motion of particles in a channel * ''Flight dynamics'', the science of aircraft and spacecraft design * ''Molecular dynamics'', the study of motion on the molecular level * '' Langevin dynamics'', a mathematical model for stochastic dynamics * '' Orbital dynamics'', the study of the motion of rockets and spacecraft * '' Stellar dynamics'', a description of the collective motion of stars * '' Vehicle dynamics, the study of vehicles in motion Generalizations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dislocations
In materials science, a dislocation or Taylor's dislocation is a linear crystallographic defect or irregularity within a crystal structure that contains an abrupt change in the arrangement of atoms. The movement of dislocations allow atoms to slide over each other at low stress levels and is known as ''glide'' or Slip (materials science), slip. The crystalline order is restored on either side of a ''glide dislocation'' but the atoms on one side have moved by one position. The crystalline order is not fully restored with a ''partial dislocation''. A dislocation defines the boundary between ''slipped'' and ''unslipped'' regions of material and as a result, must either form a complete loop, intersect other dislocations or defects, or extend to the edges of the crystal. A dislocation can be characterised by the distance and direction of movement it causes to atoms which is defined by the Burgers vector. Plasticity (physics), Plastic deformation of a material occurs by the creation and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
