Contact Conformity Effects on Spinning Torque and Friction

Dietrich, Michel; Parker, R. J.; Zaretsky, E. V.; Anderson, William J.

doi:10.1115/1.3554920

Cited by 12 publications

(6 citation statements)

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“…The resistance to this pivotal motion comes from the twisting of the contact region between the lower ball and the glass cylinder. For the present set of experimental parameters the contact region which is ≈10 µm is orders of magnitude smaller than the radius of the balls [16]. Hence the frictional resistance of the bottom ball to the pivoting motion will be negligible.…”

Section: (B) Explanationmentioning

confidence: 85%

A geometric framework for dynamics with unilateral constraints and friction, illustrated by an example of self-organized locomotion

et al. 2018

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We present a geometric framework to deal with mechanical systems which have unilateral constraints, and are subject to damping/friction, which cannot be treated within usual classical mechanics. In this new framework, the dynamical evolution of the system takes place on a multidimensional curvilinear polyhedron, and energetics near the corners of the polyhedron leads to qualitative behaviour such as stable entrapment and bifurcation. We illustrate this by an experiment in which dumbbells, placed inside a tilted hollow cylindrical drum that rotates slowly around its axis, climb uphill by forming dynamically stable pairs, seemingly against the pull of gravity.

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Section: (B) Explanationmentioning

confidence: 85%

A geometric framework for dynamics with unilateral constraints and friction, illustrated by an example of self-organized locomotion

et al. 2018

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“…When Tribogyr is compared to devices found in the literature, it clearly appears with a much wider working range. The Zaretsky, et al apparatus (Parker,et al (10); Dietrich, et al (11); Allen, et al (12)) reaches high spin but the linear speed is still equal to zero. The continuously variable toroidal drive test rig of Lingard (13) and the disc-disc apparatus of Tevaarwerk (14) allowed quite high speeds but low spinning motions compared to the Tribogyr spin range; however, Lingard's apparatus and Tribogyr have a similar normal load capacity.…”

Section: Test Rig Presentationmentioning

confidence: 95%

“…In the literature, the spin quantification is somehow questionable: some parameters defining the spin are proposed but none of them seems to give a relevant representation. Some authors directly used the normal rotational speed (in rpm or rad/s, as in Dietrich, et al (11), Allen, et al (12), and Lingard (13)) but this term does not take into account the contact geometry and thus it does not include variables that directly intervene in the physics of EHL. On the other hand, Gadallah and Dalmaz (15) and Colin et al (16) defined two parameters that take into account the mean entrainment velocity, the difference of the rotational speeds, and contact geometrical characteristics.…”

Section: Definition Of a Spin Parametermentioning

confidence: 99%

First Traction Results of High Spinning Large-Size Circular EHD Contacts from a New Test Rig: Tribogyr

Dormois

Fillot

Vergne

et al. 2009

Tribology Transactions

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This article presents a new test rig named Tribogyr and the first results obtained so far. This device allows EHL friction tests in rolling-sliding under high spinning conditions applied to large-size circular contacts. Spinning is imposed thanks to a unique design that includes a tilting facility of one of the two spindles. After a brief description of the test rig structure and of the specimen geometry, the sensor's implementation and the device capabilities are reported. The parameter used to quantify the spin in this study is then defined. It only takes into account the rotational speed normal to the contact surface and the contact radius. Then, the friction coefficient and the temperature measurements are presented. The data are at first plotted versus the classical slide-to-roll ratio and compared to numerical results obtained with and without spin. The spin parameter then is introduced to replace the slide-to-roll ratio as the varying parameter. This representation allows reporting all the results in the same figure, where the influence of the operating conditions like the entrainment speed, the tilting angle, and the slide-to-roll ratio on friction and on temperature is much more visible. It is discussed that the observed temperature difference increase is generated by an additional shearing introduced by spinning despite an observed reduction of friction.

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“…With a spinning friction tester Parker et al [2] and Dietrich et al [3] experimentally investigated the friction under pure spinning conditions. The lubricated contact consisted of a steel bearing ball and a flat with a ground cylindrical groove on it.…”

Section: Introductionmentioning

confidence: 99%

Interferometry Measurement of Spin Effect on Sliding EHL

Jiang

Guo

et al. 2008

Tribol Lett

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This paper describes interferometry measurement of the film profiles of sliding elastohydrodynamic lubrication (EHL) contacts with spin. In the custom-made EHL test rig, spin motion is introduced through adjusting the center offset of the ball-on-disc contact with respect to the disc rotation axis. A parameter, spin ratio S sp , is employed to represent the spin level, which is defined as the ratio of the Hertzian contact radius to the center offset. Experimental results show that with spin the film shape is obviously skewed, and the film thicknesses at the two side lobes are no longer the same; therefore, the symmetry of the classical horseshoe film shape is lost. The film thickness dependences on entrainment speeds are significantly influenced by the spin ratio S sp , and high spin ratios induce high speed indices. At a fixed spin ratio S sp , with increasing sliding speeds the film thickness difference between the two side lobes becomes large, and the horseshoe film shape is more distorted. When applied loads are raised, more spin is introduced, film thickness decreases, and film shape is obviously twisted.

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Contact Conformity Effects on Spinning Torque and Friction

Cited by 12 publications

References 0 publications

A geometric framework for dynamics with unilateral constraints and friction, illustrated by an example of self-organized locomotion

A geometric framework for dynamics with unilateral constraints and friction, illustrated by an example of self-organized locomotion

First Traction Results of High Spinning Large-Size Circular EHD Contacts from a New Test Rig: Tribogyr

Interferometry Measurement of Spin Effect on Sliding EHL

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