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Hydrodynamic Friction
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 in parts also understood today on the atomistic level. Concept For a contact of two fluid-lubricated surfaces, the Stribeck curve shows the rela ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tribology
Tribology is the science and engineering of understanding friction, lubrication and wear phenomena for interacting surfaces in relative Motion (physics), motion. It is highly interdisciplinary, drawing on many academic fields, including physics, chemistry, materials science, mathematics, biology and engineering. The fundamental objects of study in tribology are tribosystems, which are physical systems of contacting surfaces. Subfields of tribology include biotribology, nanotribology and space tribology. It is also related to other areas such as the coupling of corrosion and tribology in tribocorrosion and the contact mechanics of how surfaces in contact deform. Approximately 20% of the total energy expenditure of the world is due to the impact of friction and wear in the transportation, manufacturing, power generation, and residential sectors. Etymology The word ''tribology'' derives from the Ancient Greek, Greek root τριβ- of the verb , ''wiktionary:tribo-, tribo'', "I rub" in ... [...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. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of the processes involved is called tribology, and has a history of more than 2000 years. Friction can have dramatic consequences, as illustrated by the use of friction created by rubbing pieces of wood together to start a fire. Another important consequence of many types of friction can be wear, which may lead to performance degradation or damage to components. It is known that frictional energy losses account for about 20% of the total energy expenditure of the world. As briefly discussed later, there are many different contributors to the retarding force in friction, ranging from asperity deformation to the generation of charges and changes in local structure. When two bodies in contact move relative to each other, due to these variou ... [...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 private military-industrial laboratory (Center for Scientific-Technical Research) 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mayo D
Mayo often refers to: * Mayonnaise, a sauce * County Mayo, in the west of Ireland * Mayo Clinic, a medical center in Rochester, Minnesota, United States * Mayo (surname), includes a list of people with the name 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) * County Mayo (Parliament of Ireland constituency) * County Mayo (UK Parliament constituency) * Mayo, County Mayo, a village Ivory Coast * Mayo, Ivory Coast, a town and commune Sudan * Mayo, Khartoum, a neighborhood Thailand * Mayo district, Pattani United Kingdom * Mayo, a townland in County Down, Northern Ireland * Mayo (UK Parliament constit ... [...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 fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid
In physics, a fluid is a liquid, gas, or other material that may continuously motion, move and Deformation (physics), deform (''flow'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are Matter, 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 have both fluid and solid properties. Non-Newtonian 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 (resin), 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 to any liquid constituent of the body (body fluid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viscosity
Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for example, syrup has a higher viscosity than water. Viscosity is defined scientifically as a force multiplied by a time divided by an area. Thus its SI units are newton-seconds per metre squared, or pascal-seconds. Viscosity quantifies the internal friction, 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 center line than near its walls. Experiments show that some stress (physics), 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 ... [...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. By repelling water and other substances, it also reduces corrosion. 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 incre ... [...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. An understanding of the concept of asperities is required for any understanding of the field of Tribology, or the scientific study of friction, wear, and lubrication. Expanding on the linkage between asperities and seismology, asperities are critical in the understanding of geophysical faults via elastic deformation. These faults, such as the San Andreas fault line, te ... [...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 and baking to prevent food sticking), to reduce rusting and friction in machinery, through the use of motor oil and Grease (lubricant), grease, bioapplications on humans (e.g., lubricants for Replacement joint, artificial joints), ultrasound examination, medical examination, and sexual intercourse. It is mainly used to reduce friction and to contribute to a better, more efficient functioning of a mechanism. History Lubricants have been in some use for thousands of year ... [...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, which are adapted to living in the taiga, and 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 describe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berlin
Berlin ( ; ) is the Capital of Germany, capital and largest city of Germany, by both area and List of cities in Germany by population, population. With 3.7 million inhabitants, it has the List of cities in the European Union by population within city limits, highest population within its city limits of any city in the European Union. The city is also one of the states of Germany, being the List of German states by area, third smallest state in the country by area. Berlin is surrounded by the state of Brandenburg, and Brandenburg's capital Potsdam is nearby. The urban area of Berlin has a population of over 4.6 million and is therefore the most populous urban area in Germany. The Berlin/Brandenburg Metropolitan Region, Berlin-Brandenburg capital region has around 6.2 million inhabitants and is Germany's second-largest metropolitan region after the Rhine-Ruhr region, as well as the List of EU metropolitan areas by GDP, fifth-biggest metropolitan region by GDP in the European Union. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
