Bestimmung einiger Reibungscoëfficienten und Versuche über den Einfluss der Magnetisirung und Electrisirung auf die Reibung der Flüssigkeiten

König, Walter

doi:10.1002/andp.18852610807

Cited by 17 publications

(1 citation statement)

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“…To study the parameters affecting the speed of settling (V), we use the famous Stokes' formulation for a sphere moving slowly under gravitational forces. The result is: 2a2(P_P0) (1) 9j where a is the sphere diameter, p is the density ofparticles, Po that ofthe carrier liquid, is the viscosity of the carrier liquid, and g is the gravitational acceleration. Of course, this formulation is very simplistic in that it ignores the interaction of the particles and, hence, is invalid for highly concentrated systems.…”

Section: Sedimental Stabilitymentioning

confidence: 99%

<title>Manufacturing and characterization of magnetorheological fluids</title>

et al. 1997

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Magnetorheological (MR) fluids are stable suspensions of magnetic particles in a carrying fluid exhibiting controllable rheological behavior in the presence of a magnetic field. Magnetorheological effect represents a reversible increase, due to an external magnetic field, of effective viscosity. MR fluids and devices have the potential to revolutionize the design of hydraulic systems, actuators, valves, active shock and vibration dampers, and other components used in mechanical systems. MR fluids that are currently available suffer from high initial viscosity values and low stability. Hence, there is a compelling need to optimize the MR fluid manufacturing process to produce optimum MR fluid characteristics. The present study proposes to manufacture an optimum composition of a MR fluid in terms of its quality and properties. A high-speed bead mill blending machine is used to manufacture the fluid. Characterization studies are conducted to evaluate the produced fluid.Keywords: magnetorheological fluids, optimum composition, bead mill machine, characterization INTRODUCTIONMagnetorheological (MR) fluids are stable suspensions of very fine ferromagnetic particles in a non-magnetic carrying medium exhibiting controllable rheological behavior in the presence of an applied magnetic field. In moderate fields, the apparent viscosity of MR fluids increases by more than two orders of magnitude. Electrorheological (ER) fluids, which are composed of suspended dielectric particles in a non-polar medium, exhibit a similar behavior to MR fluids in the presence of an external electric field. Both MR and ER fluids are part of a new class of controllable fluids that has the potential to revolutionize the design of hydraulic and electromechanical systems.The first observations of a controllable fluid behavior in the presence of an electric field were reported by Konig1 and Duff2 However, ER fluids were first invented by Winslow when he filed a patent on a ER clutch-type relay. This clutch closed the relay contacts in response to a vacuum tube photocell connected in series with a supply of 120 volts. This ER controllable fluid behavior was, ever since, referred to as the Winslow effect. On the other hand, MR fluids were invented by Rabinow4 when he devised a magnetic fluid clutch. Since then, there have been hundreds of patents and conducted research on these controllable fluids. However, until the last decade, the development of these fluids was largely ignored. As Winslow himself puts it5, this might have been "since no great necessity for this invention could be imagined" at that time.Nowadays, proposed applications of controllable fluids are both numerous and of enormous potential value. Changes in a variety of material properties, such as magnetic, electrical, thermal, acoustic, and other mechanical and physical properties can be observed in MR or ER fluids upon the application of a magnetic or electric field, respectively. However, most of the applications that have been studied in some detail are based on the controllable rheo...

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Section: Sedimental Stabilitymentioning

confidence: 99%

<title>Manufacturing and characterization of magnetorheological fluids</title>

et al. 1997

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Electrorheology

Resca

1999

Wiley Encyclopedia of Electrical and Electronics Engineering

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The sections in this article are Composition and Properties of ER Fluids Basic Requirements for Engineering and Commercial Applications of ER Fluids Functioning and Design of Basic ER Devices Newtonian Fluids and Elastic Solids Non‐Newtonian Fluids ER Fluid Rheology ER Fluid Rheometry Theoretical Models and Simulations of ER Phenomena Theory and Computation of Electrical Interactions in ER Fluids

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Ueber die Bestimmung von Reibungscoëfficienten tropfbarer Flüssigkeiten mittelst drehender Schwingungen

König

1887

Annalen der Physik

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Ueber die Bestimmwbg von ReibungscoZfficienteot tropf barer FZussigIceiten mittelst drehenderSchwiiqpmgen; uon W r r t t e r R8miy. (Hlerm Tar. I1 FIE. 1-8.) Es ist eiiie bekannte Thatsache, dass die Berechnung von Reibungscoefficienten tropfbarer Fliissigkeiten aus der Amplitudenabnahme drehender Schwingungen grossere Werthe filr diese Coefficienten ergiebt, als die Untersuchung des Stromens durch Capillarrohren. Bus dem logarithmischen Decrement der Schwingungen einer mit Wasser gefullten Hohlkugel fanden die Hrn. v. H e l m h o l t z und v. Piotrowski') die Reibungsconstante des Wassers im Verhaltniss von 5 zu 4 grosser als P o is e uill e mittelst Ausflussversuchen, und dieselbe Constante f a d Hr. 0. E. M e y c r 2 ) nach der Coulomb'schon Methode schwingender Scheibeii im Verhaltniss von 6 zu 5 grosser als P o i s e u i l l e . Die Unterschiede sind also betrachtlich, und sie sind, wie ich selbst schon friiher einmal festzustellen Gelegenheit hatte 3), uni so grosser, je griisser die Zteibungsconstante selbsr ist. E. M e y e r erklart in der citirten Abhandlung dieso Verschiedenheiten als begriindet in den Annahmen, welche zur Gewinnung brauchbarer Formeln in die theoretische Entwicklung eingcfiihrt wurden ; die dabei cintretenden Vernachlilssigungen waren in dem Falle schwingender Scheiben derart, dass der Reibungscocfficient zu gross, in dem Falle des Ausflusscs durch Capillarrohren derart, dass er zu klein Hr. 0 1) 11. v. Helmholtz 11. G. v. P i o t r o w s k i , Wien. 195 sigkeiten specie11 die Beziehung zwischen der Schwingungsdauer und dem logarithmischen Decremente der schwingenden Kugeln untersucht und die Darstellung dieser Beobachtungen durch die theoretisch gefundenen Formeln zum Prufstein der Theorie gemacht. Die Resultate, die sich dabei fur die numerischen Werthe der Reibungsconstanten ergaben, haben mich dann weiter dazu gefiihrt, diese Untersuchungsmethode auch auf die Scheibenversuche auszudehnen. Die Theorie der DBmpfung schwingender Kugeln.Es bedeutet im Folgenden: 7 den Reibungscoefficienten des Mittels, p die Dichtigkeit desselben,

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Bestimmung einiger Reibungscoëfficienten und Versuche über den Einfluss der Magnetisirung und Electrisirung auf die Reibung der Flüssigkeiten

Cited by 17 publications

References 2 publications

<title>Manufacturing and characterization of magnetorheological fluids</title>

<title>Manufacturing and characterization of magnetorheological fluids</title>

Electrorheology

Ueber die Bestimmung von Reibungscoëfficienten tropfbarer Flüssigkeiten mittelst drehender Schwingungen

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