|
Stribeck Curve
The Stribeck curve is a fundamental concept in the field of tribology. It shows that friction in fluid-lubricated contacts is a non-linear function of the contact load, the lubricant viscosity and the lubricant entrainment speed. The discovery and underlying research is usually attributed to Richard StribeckStribeck, R. (1901), Kugellager für beliebige Belastungen (Ball Bearings for any Stress), Zeitschrift des Vereins Deutscher Ingenieure 45.Stribeck, R. (1902), Die wesentlichen Eigenschaften der Gleit- und Rollenlager (Characteristics of Plain and Roller Bearings), Zeit. des VDI 46. and Mayo D. Hersey, who studied friction in journal bearings for railway wagon applications during the first half of the 20th century; however, other researchers have arrived at similar conclusions before. The mechanisms along the Stribeck curve have been understood today also on the atomistic level. Concept For a contact of two fluid-lubricated surfaces, the Stribeck curve shows the relationsh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tribology
Tribology is the science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication and wear. Tribology is highly interdisciplinary, drawing on many academic fields, including physics, chemistry, materials science, mathematics, biology and engineering. People who work in the field of tribology are referred to as ''tribologists''. The fundamental objects of study in tribology are tribosystems, which are physical systems of contacting surfaces. In lubricated tribosystems, contact stress can create tribofilms. Subfields of tribology include biotribology, nanotribology, space tribology and tribotronics. Etymology The word ''tribology'' derives from the Greek root τριβ- of the verb , '' tribo'', "I rub" in classic Greek, and the suffix '' -logy'' from , ''-logia'' "study of", "knowledge of". Peter Jost coined the word in 1966, in the eponymous report which highlighted the cost of friction, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into ''static friction'' ("stiction") between non-moving surfaces, and ''kinetic friction'' between moving surfaces. With the exception of atomic or molecular friction, dry friction generally arises from the interaction of surface features, known as asperities (see Figure 1). *Fluid friction describes the friction between layers of a viscous fluid that are moving relative to each other. *Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces. *Skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body. *Internal friction is the force resisting motion between the elements making up a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard Stribeck
Richard Stribeck (7. July 1861 in Stuttgart , † 29. March 1950) was a German engineer, after whom the Stribeck Curve is named. Life Stribeck studied mechanical engineering in 1880 at the Technical University of Stuttgart in 1885 and worked as a designer in Königsberg. In 1888 he became professor in Stuttgart, and 1890 Professor of Mechanical Engineering at the Technical University of Darmstadt. 1893 he took a professorship at the Dresden Technical University. In 1896 he became head of the laboratory equipment of the university. In 1898 was head of the Stribeck Physical metallurgy department of the Technical Institute and director of the center for scientific and technical studies in Neubabelsberg. In 1902 he described the friction coefficient in lubricated bearings, now known as the Stribeck curve. From 1908 Stribeck worked for the Friedrich Krupp AG in Essen in 1919 at the Robert Bosch GmbH in Stuttgart. Stribeck was a college friend of the industrialist Robert Bosch, with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mayo D
Mayo often refers to: * Mayonnaise, often shortened to "mayo" * Mayo Clinic, a medical center in Rochester, Minnesota, United States Mayo may also refer to: Places Antarctica * Mayo Peak, Marie Byrd Land Australia * Division of Mayo, an Australian Electoral Division in South Australia Canada * Mayo, Quebec, a municipality * Mayo, Yukon, a village ** Mayo (electoral district), Yukon, a former electoral district Cape Verde * Maio, Cape Verde (also formerly known as Mayo Island) Republic of Ireland * County Mayo * Mayo (Dáil constituency) * Mayo (Parliament of Ireland constituency) * Mayo (UK Parliament constituency) * Mayo, County Mayo, a village Ivory Coast * Mayo, Ivory Coast, a town and commune Thailand * Mayo District, Pattani Province United Kingdom * Mayo, a townland in County Down, Northern Ireland * Mayo (UK Parliament constituency), a former constituency encompassing the whole of County Mayo United States * Mayo, Florida, a town * Mayo, Kentucky, an uninc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Curva Di Stribeck
Curva (plural: ''curve'' ) is an Italian term or name for curved stands of seating located at sports stadiums, particularly in Italy; so named, originally, due to their curved or bending shape. The curva plays an integral part in the culture of Ultras and European football. Composition The majority of stands referred to as a "curva" are located behind the goals in their respective stadiums and contain the most vocal supporters within them, often known as Ultras. They are usually curved in shape, in some form whether minor or major, often due to the presence of a running track around the pitch. The Stadio Giuseppe Meazza provides an example of two prominent stands referred to as "curva", " Curva Nord" and " Curva Sud", which contain only minor curves at their corners, while the Stadio Olimpico provides an example of two completely curved stands. A curva may extend from one corner flag to another or be located centrally behind the goal, bordered by two separate corner sections ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid
In physics, a fluid is a liquid, gas, or other material that continuously deforms (''flows'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are substances which cannot resist any shear force applied to them. Although the term ''fluid'' generally includes both the liquid and gas phases, its definition varies among branches of science. Definitions of ''solid'' vary as well, and depending on field, some substances can be both fluid and solid. Viscoelastic fluids like Silly Putty appear to behave similar to a solid when a sudden force is applied. Substances with a very high viscosity such as pitch appear to behave like a solid (see pitch drop experiment) as well. In particle physics, the concept is extended to include fluidic matters other than liquids or gases. A fluid in medicine or biology refers any liquid constituent of the body (body fluid), whereas "liquid" is not used in this sense. Sometimes liquids given for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viscosity
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the internal frictional force between adjacent layers of fluid that are in relative motion. For instance, when a viscous fluid is forced through a tube, it flows more quickly near the tube's axis than near its walls. Experiments show that some stress (such as a pressure difference between the two ends of the tube) is needed to sustain the flow. This is because a force is required to overcome the friction between the layers of the fluid which are in relative motion. For a tube with a constant rate of flow, the strength of the compensating force is proportional to the fluid's viscosity. In general, viscosity depends on a fluid's state, such as its temperature, pressure, and rate of deformation. However, the dependence on some of these properties is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lubrication
Lubrication is the process or technique of using a lubricant to reduce friction and wear and tear in a contact between two surfaces. The study of lubrication is a discipline in the field of tribology. Lubrication mechanisms such as fluid-lubricated systems are designed so that the applied load is partially or completely carried by hydrodynamic or hydrostatic pressure, which reduces solid body interactions (and consequently friction and wear). Depending on the degree of surface separation, different lubrication regimes can be distinguished. Adequate lubrication allows smooth, continuous operation of machine elements, reduces the rate of wear, and prevents excessive stresses or seizures at bearings. When lubrication breaks down, components can rub destructively against each other, causing heat, local welding, destructive damage and failure. Lubrication mechanisms Fluid-lubricated systems As the load increases on the contacting surfaces, distinct situations can be observed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asperity (materials Science)
In materials science, asperity, defined as "unevenness of surface, roughness, ruggedness" (from the Latin ''asper''—"rough"), has implications (for example) in physics and seismology. Smooth surfaces, even those polished to a mirror finish, are not truly smooth on a microscopic scale. They are rough, with sharp, rough or rugged projections, termed "asperities". Surface asperities exist across multiple scales, often in a self affine or fractal geometry. The fractal dimension of these structures has been correlated with the contact mechanics exhibited at an interface in terms of friction and contact stiffness. When two macroscopically smooth surfaces come into contact, initially they only touch at a few of these asperity points. These cover only a very small portion of the surface area. Friction and wear originate at these points, and thus understanding their behavior becomes important when studying materials in contact. When the surfaces are subjected to a compressive load, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lubricant
A lubricant (sometimes shortened to lube) is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, transporting foreign particles, or heating or cooling the surfaces. The property of reducing friction is known as lubricity. In addition to industrial applications, lubricants are used for many other purposes. Other uses include cooking ( oils and fats in use in frying pans, in baking to prevent food sticking), bioapplications on humans (e.g. lubricants for artificial joints), ultrasound examination, medical examination, and sexual intercourse. It is mainly used to reduce friction and to contribute to a better and efficient functioning of a mechanism. History Lubricants have been in some use for thousands of years. Calcium soaps have been identified on the axles of chariots dated to 1400 BC. Building stones were slid on oil-impregrate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Martens Curves
A marten is a weasel-like mammal in the genus ''Martes'' within the subfamily Guloninae, in the family Mustelidae. They have bushy tails and large paws with partially retractile claws. The fur varies from yellowish to dark brown, depending on the species; it is valued by animal trappers for the fur trade. Martens are slender, agile animals, adapted to living in the taiga, which inhabit coniferous and northern deciduous forests across the Northern Hemisphere. Classification Results of DNA research indicate that the genus ''Martes'' is paraphyletic, with some studies placing ''Martes americana'' outside the genus and allying it with ''Eira'' and ''Gulo'', to form a new New World clade. The genus first evolved up to seven million years ago during the Miocene epoch. Fossils Several fossil martens have been described, including: *†''Martes campestris'' (Pliocene) *†''Martes wenzensis'' (Pliocene) *†''Martes vetus'' (Pleistocene) Another described fossil species, ''Ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berlin
Berlin ( , ) is the capital and List of cities in Germany by population, largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's List of cities in the European Union by population within city limits, most populous city, according to population within city limits. One of Germany's States of Germany, sixteen constituent states, Berlin is surrounded by the Brandenburg, State of Brandenburg and contiguous with Potsdam, Brandenburg's capital. Berlin's urban area, which has a population of around 4.5 million, is the second most populous urban area in Germany after the Ruhr. The Berlin/Brandenburg Metropolitan Region, Berlin-Brandenburg capital region has around 6.2 million inhabitants and is Metropolitan regions in Germany, Germany's third-largest metropolitan region after the Rhine-Ruhr and Frankfurt Rhine-Main, Rhine-Main regions. Berlin straddles the banks of the Spree (river), Spree, which flows into the Havel (a tributary of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
