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Boundary Friction
Boundary friction occurs when a surface is at least partially wet, but not so lubricated that there is no direct friction between two surfaces. The Effect When two consistent, unlubricated surfaces slide against each other, there is a specific, predictable amount of friction that occurs. This amount increases as velocity does, but only up to a certain point. That increase generally follows what is known as a Stribeck curve, after Richard Stribeck. On the other hand, if the two surfaces are completely lubricated, there is no direct friction or rubbing at all. In real life, though, there is often a situation where the surfaces are not completely dry, but also not so lubricated that they do not touch. This "boundary friction" produces various effects, like an increase in lubrication through the generation of shearing force In solid mechanics, shearing forces are unaligned forces acting on one part of a body in a specific direction, and another part of the body in the opposit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 relationship ... [...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 who ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shearing Force
In solid mechanics, shearing forces are unaligned forces acting on one part of a Rigid body, body in a specific direction, and another part of the body in the opposite direction. When the forces are collinear (aligned with each other), they are called tension forces and compression forces. William A. Nash defines shear force in terms of Plane (geometry), planes: "If a plane is passed through a body, a force acting along this plane is called a ''shear force'' or ''shearing force''." Force required to shear steel This section calculates the force required to cut a piece of material with a shearing action. The relevant information is the area of the material being sheared, ie the area across which the shearing action takes place, and the shear strength of the material. A round bar of steel is used as an example. The shear strength is calculated from the tensile strength using a factor which relates the two strengths. In this case 0.6 applies to the example steel, known as EN8 br ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
