Microscopic friction emulators
نویسندگان
چکیده
منابع مشابه
Macroscopic diagnostics of microscopic friction phenomena.
We show that the static friction force which must be overcome to render a sticking contact sliding is reduced if an external torque is also exerted. As a test system we study a planar disk lying on a horizontal flat surface. We perform experiments and compare with analytical results to find that the coupling between static friction force and torque is nontrivial: It is not determined by the Cou...
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Atomically flat and clean metal surfaces exhibit a regime of ultra-low friction at low normal loads. Atomic force microscopy, performed in ultra-high vacuum on Cu(100) and Au(111) surfaces, reveals a clear stick-slip modulation in the lateral force but almost zero dissipation. Significant friction is observed only for higher loads (*4– 6 nN above the pull-off force) together with the onset of w...
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We demonstrate that lateral vibrations of a substrate can dramatically increase surface diffusivity and mobility and reduce friction at the nanoscale. Dilatancy is shown to play an essential role in the dynamics of a nanometer-size tip which interacts with a vibrating surface. We find an abrupt dilatancy transition from the state with a small tip-surface separation to the state with a large sep...
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A microscopic theory for the ubiquitous phenomenon of static friction is presented. Interactions between two surfaces are modeled by an energy penalty that increases exponentially with the degree of surface overlap. The resulting static friction is proportional to load, in accordance with Amontons's laws. However, the friction coefficient between bare surfaces vanishes as the area of individual...
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Granular media are prevalent in dynamic frictional processes throughout nature and technology, from earthquakes to grain transport. Empirical relations describing macroscopic friction as a function of the inertial number have proven successful in predicting experimentally observed velocity and stress profi les when combined with continuum models. However, these relations and the continuum model...
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ژورنال
عنوان ژورنال: Nature
سال: 2015
ISSN: 0028-0836,1476-4687
DOI: 10.1038/526332a