|
Fatigue Limit
The fatigue limit or endurance limit is the stress (mechanics), stress level below which an infinite number of loading cycles can be applied to a material without causing fatigue (material), fatigue failure. Some metals such as ferrous alloys and titanium alloys have a distinct limit, whereas others such as aluminium and copper do not and will eventually fail even from small stress amplitudes. Where materials do not have a distinct limit the term fatigue strength or endurance strength is used and is defined as ''the maximum value of completely reversed bending stress that a material can withstand for a specified number of cycles without a fatigue failure''. For polymeric materials, the fatigue limit is also commonly known as the intrinsic strength. Definitions The ASTM International, ASTM defines ''fatigue strength'', S_, as "the value of stress at which failure occurs after N_f cycles", and ''fatigue limit'', S_f, as "the limiting value of stress at which failure occurs as N_f be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rolling Bearing
In mechanical engineering, a rolling-element bearing, also known as a rolling bearing,ISO 15 is a bearing which carries a load by placing rolling elements (such as balls, cylinders, or cones) between two concentric, grooved rings called races. The relative motion of the races causes the rolling elements to roll with very little rolling resistance and with little sliding. One of the earliest and best-known rolling-element bearings is a set of logs laid on the ground with a large stone block on top. As the stone is pulled, the logs roll along the ground with little sliding friction. As each log comes out the back, it is moved to the front where the block then rolls onto it. It is possible to imitate such a bearing by placing several pens or pencils on a table and placing an item on top of them. See " bearings" for more on the historical development of bearings. A rolling element rotary bearing uses a shaft in a much larger hole, and spheres or cylinders called "rollers" tigh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elasticity (physics)
In physics and materials science, elasticity is the ability of a body to resist a distorting influence and to return to its original size and shape when that influence or force is removed. Solid objects will deform when adequate loads are applied to them; if the material is elastic, the object will return to its initial shape and size after removal. This is in contrast to ''plasticity'', in which the object fails to do so and instead remains in its deformed state. The physical reasons for elastic behavior can be quite different for different materials. In metals, the Crystal structure, atomic lattice changes size and shape when forces are applied (energy is added to the system). When forces are removed, the lattice goes back to the original lower energy state. For rubber elasticity, rubbers and other polymers, elasticity is caused by the stretching of polymer chains when forces are applied. Hooke's law states that the force required to deform elastic objects should be Prop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fatigue (material)
In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts of the fracture surface. The crack will continue to grow until it reaches a critical size, which occurs when the stress intensity factor of the crack exceeds the fracture toughness of the material, producing rapid propagation and typically complete fracture of the structure. Fatigue has traditionally been associated with the failure of metal components which led to the term metal fatigue. In the nineteenth century, the sudden failing of metal railway axles was thought to be caused by the metal crystallising because of the brittle appearance of the fracture surface, but this has since been disproved. Most materials, such as composites, plastics and ceramics, seem to experience some sort of fatigue-related failure. To aid in predicting the f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paul C
Paul C. McKasty (September 20, 1964July 17, 1989), better known as Paul C, was an American East Coast hip hop pioneer, producer, engineer, and mixer in the 1980s.Pritt Kalsi McKasty gained recognition for his work with notable artists such as Devo, Organized Konfusion, Kwamé, Queen Latifah, Biz Markie, Ultramagnetic MCs, Rahzel, and Eric B & Rakim. ''Complex'' called him "one of the most important figures in the development of sampling" and Questlove of the Roots called McKasty, "damn near the J Dilla of his day." Work Paul gave himself the middle name "Charles" after Ray Charles, which he shortened to the initial "C". He developed an interest in music from his older brother Michael, who was a guitarist, and Tim, who worked as a recording engineer at 1212 Studio in Queens. According to Paul's middle school friend TeQnotic, he was an already gifted artist and bass guitar player in junior high. McKasty began his musical career as a bassist of the pop rock band the Mandolindle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wilhelm Batz
Wilhelm Batz (21 May 1916 – 11 September 1988) was a German Luftwaffe fighter ace during World War II. A flying ace or fighter ace is a military aviator credited with shooting down five or more aircraft during aerial combat. Batz flew 445 combat missions and claimed 237 aircraft shot down; 234 victories were achieved over the Eastern Front, including at least 46 Ilyushin Il-2 ground-attack aircraft. Batz claimed three victories, including one four-engine bomber against the United States Army Air Forces (USAAF) over the Ploieşti oil fields. Following the war, he served in the German Air Force of the Federal Republic of Germany (West Germany). Born in Bamberg, Batz joined the Luftwaffe in 1935 and completed his flight training in 1939. Batz then served as a flight instructor before he was trained as fighter pilot. In February 1943, Batz was transferred to II. '' Gruppe'' (2nd Group) of ''Jagdgeschwader'' 52 (JG 52—52nd Fighter Wing) which was on the Eastern Front. Ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johann Bauschinger
Johann Bauschinger (11 June 1834, in Nuremberg – 25 November 1893, in Munich) was a mathematician, builder, and professor of Engineering Mechanics at Munich Polytechnic, from 1868 until his death. The Bauschinger effect in materials science Materials science is an interdisciplinary field of researching and discovering materials. Materials engineering is an engineering field of finding uses for materials in other fields and industries. The intellectual origins of materials sci ... is named after him. He was also the father of astronomer Julius Bauschinger (1860–1934). References *. * External links 1834 births 1893 deaths Scientists from Nuremberg 19th-century German mathematicians Academic staff of the Technical University of Munich Mathematicians from the Kingdom of Bavaria Mathematicians from the German Empire {{Germany-mathematician-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
August Wöhler
August Wöhler (22 June 1819 – 21 March 1914) was a German railway engineer, best remembered for his systematic investigations of metal fatigue. Life Born in the town of Soltau, Hanover, the son of local teacher Georg Heinrich Wöhler, he showed early mathematical ability and won a scholarship to study at the Higher Vocational College of Hannover from 1835, under the direction of Karl Karmarsch. In 1840, he was recruited to the Borsig works in Berlin where he worked on the manufacture of rail tracks. In 1843, after a brief stay in Hannover, he started to receive instruction in locomotive driving in Belgium, returning as an engineer on the Hanover-Brunswick line of the Royal Hanoverian State Railways. By 1847, Wöhler was chief superintendent of rolling stock on the Lower Silesian-Marcher railway in Frankfurt (Oder). The railroad was nationalised by the Prussian state railways in 1852 and Wöhler's growing reputation led to his appointment by the Prussian Ministry of Comme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wilhelm Albert (engineer)
Wilhelm Bedzheit Albert (24 January 1787 – 4 July 1846) was a German engineer and mining administrator, best remembered as the first person to record observations of metal fatigue. Albert was born in Hanover and showed early talent as a musician before embarking on the study of law in Göttingen in 1803. Experience in the Harz mountains awakened an interest in mining and, in 1806, he was appointed to the Mining and Forestry Office in Clausthal. By 1836 he was directing the entire mining industry of the Harz region. In 1829, he observed, studied and reported the failure of iron mine hoist chains arising from repeated small loadings, the first recorded account of metal fatigue. He built a machine which repeatedly loaded a chain. His finding was that fatigue was not associated with an accidental overload, but was dependent on load and the number of repetitions of load cycles. He invented a twisted steel cable, later known as an "Albert Rope", which was first used in the Claus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ozone Cracking
Cracks can be formed in many different elastomers by ozone attack, and the characteristic form of attack of vulnerable rubbers is known as ozone cracking. The problem was formerly very common, especially in tires, but is now rarely seen in those products owing to preventive measures. However, it does occur in many other safety-critical items such as fuel lines and rubber seals, such as gaskets and O-rings, where ozone attack is considered unlikely. Only a trace amount of the gas is needed to initiate cracking, and so these items can also succumb to the problem. Susceptible elastomers Tiny traces of ozone in the air will attack double bonds in rubber chains, with natural rubber, polybutadiene, styrene-butadiene rubber and nitrile rubber being most sensitive to degradation.Layer, R. W., & Lattimer, R. P. (1990). Protection of rubber against ozone. Rubber Chemistry and Technology, 63(3), 426-450. Every repeat unit in the first three materials has a double bond, so every unit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stress (mechanics)
In continuum mechanics, stress is a physical quantity that describes forces present during deformation. For example, an object being pulled apart, such as a stretched elastic band, is subject to ''tensile'' stress and may undergo elongation. An object being pushed together, such as a crumpled sponge, is subject to ''compressive'' stress and may undergo shortening. The greater the force and the smaller the cross-sectional area of the body on which it acts, the greater the stress. Stress has dimension of force per area, with SI units of newtons per square meter (N/m2) or pascal (Pa). Stress expresses the internal forces that neighbouring particles of a continuous material exert on each other, while ''strain'' is the measure of the relative deformation of the material. For example, when a solid vertical bar is supporting an overhead weight, each particle in the bar pushes on the particles immediately below it. When a liquid is in a closed container under pressure, each ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steel
Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength and low raw material cost, steel is one of the most commonly manufactured materials in the world. Steel is used in structures (as concrete Rebar, reinforcing rods), in Bridge, bridges, infrastructure, Tool, tools, Ship, ships, Train, trains, Car, cars, Bicycle, bicycles, Machine, machines, Home appliance, electrical appliances, furniture, and Weapon, weapons. Iron is always the main element in steel, but other elements are used to produce various grades of steel demonstrating altered material, mechanical, and microstructural properties. Stainless steels, for example, typically contain 18% chromium and exhibit improved corrosion and Redox, oxidation resistance versus its carbon steel counterpart. Under atmospheric pressures, steels generally ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
