Critical Wedging Coefficient in Planar Frictional System

2021 ◽  
pp. 111405
Author(s):  
Sangkyu Kim ◽  
Yong Hoon Jang
Keyword(s):  
Frictional System

scholarly journals Ternary Logic of Motion to Resolve Kinematic Frictional Paradoxes

Entropy ◽  
2019 ◽  
Vol 21 (6) ◽  
pp. 620 ◽  
Author(s):  
Michael Nosonovsky ◽  
Alexander D. Breki
Keyword(s):  
Dry Friction ◽  
Sliding Friction ◽  
Rigid Bodies ◽  
Newtonian Mechanics ◽  
Stability Criteria ◽  
Ternary Logic ◽  
Elastic Bodies ◽  
Logic Approach ◽  
Frictional System ◽  
Painlevé Paradoxes

Paradoxes of dry friction were discovered by Painlevé in 1895 and caused a controversy on whether the Coulomb–Amontons laws of dry friction are compatible with the Newtonian mechanics of the rigid bodies. Various resolutions of the paradoxes have been suggested including the abandonment of the model of rigid bodies and modifications of the law of friction. For compliant (elastic) bodies, the Painlevé paradoxes may correspond to the friction-induced instabilities. Here we investigate another possibility to resolve the paradoxes: the introduction of the three-value logic. We interpret the three states of a frictional system as either rest-motion-paradox or as rest-stable motion-unstable motion depending on whether a rigid or compliant system is investigated. We further relate the ternary logic approach with the entropic stability criteria for a frictional system and with the study of ultraslow sliding friction (intermediate between the rest and motion or between stick and slip).

Numerical Modeling of Friction-Induced Vibrations and Dynamic Instabilities

1994 ◽  
Vol 47 (7) ◽  
pp. 255-274 ◽  
Author(s):  
W. W. Tworzydlo ◽  
E. B. Becker ◽  
J. T. Oden
Keyword(s):  
Numerical Study ◽  
Normal Modes ◽  
Friction Model ◽  
Rigid Bodies ◽  
Stick Slip ◽  
Quantitative Correlation ◽  
Frictional System ◽  
Pin On Disk ◽  
Stick Slip Motion ◽  
Slip Motion

A numerical study of dynamic instabilities and vibrations of mechanical systems with friction is presented. Of particular interest are friction-induced vibrations, self-excited oscillations and stick-slip motion. A typical pin-on-disk apparatus is modeled as the assembly of rigid bodies with elastic connections. An extended version of the Oden-Martins friction model is used to represent properties of the interface. The mechanical model of the frictional system is the basis for numerical analysis of dynamic instabilities caused by friction and of self-excited oscillations. Coupling between rotational and normal modes is the primary mechanism of resulting self-excited oscillations. These oscillations combine with high-frequency stick-slip motion to produce a significant reduction of the apparent kinetic coefficient of friction. As a particular study model, a pin-on-disk experimental setup has been selected. A good qualitative and quantitative correlation of numerical and experimental results is observed.

Stabilization of Frictional Sliding by Normal Load Modulation

2003 ◽  
Vol 70 (2) ◽  
pp. 220-226 ◽  
Author(s):  
A. Cochard ◽  
L. Bureau ◽  
T. Baumberger
Keyword(s):  
Normal Load ◽  
Modulation Frequency ◽  
Shear Stiffness ◽  
Quantitative Agreement ◽  
Stability Diagram ◽  
Polymer Materials ◽  
Stick Slip ◽  
Classical State ◽  
Rate Dependent ◽  
Frictional System

This paper presents the stability analysis of a system sliding at low velocities (<100 μm⋅s−1) under a periodically modulated normal load, preserving interfacial contact. Experiments clearly evidence that normal vibrations generally stabilize the system against stick-slip oscillations, at least for a modulation frequency much larger than the stick-slip one. The mechanical model of L. Bureau, T. Baumberger, and C. Caroli validated on the steady-state response of the system, is used to map its stability diagram. The model takes explicitly into account the finite shear stiffness of the load-bearing asperities, in addition to a classical state and rate-dependent friction force. The numerical results are in excellent quantitative agreement with the experimental data obtained from a multicontact frictional system between glassy polymer materials. Simulations at larger amplitude of modulation (typically 20 percent of the mean normal load) suggest that the nonlinear coupling between normal and sliding motion could have a destabilizing effect in restricted regions of the parameter space.

In Vitro Evaluation of the Removal Force of Abutments in Frictional Dental Implants

2011 ◽  
Vol 37 (5) ◽  
pp. 519-523 ◽  
Author(s):  
João César Zielak ◽  
Murilo Rorbacker ◽  
Rodrigo Gomes ◽  
Celso Yamashita ◽  
Carla Castiglia Gonzaga ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Body Weight ◽  
Dental Implants ◽  
Dental Implant ◽  
Compression Force ◽  
Implant Abutment ◽  
Frictional System ◽  
Different Diameters ◽  
The Impact

The objective of the present work was to determine some force parameters for removal of an abutment from a dental implant in a frictional system (locking taper, 1.23 degrees). Ten implants of the same length (11 mm) and different diameters were selected, along with 10 straight abutments (13 mm length) with different diameters. Abutments were attached to implants without application of force. Fixation of the implant-abutment mount (IA) (repeated 1–5 times) was performed through the impact of a body weight (compression force, tapping) left from a known height. After each group of tappings, IA mounts were coupled with a tensile strength tester. The lowest removal value was found after the first tapping of mount #2 (83 N, implant diameter 3.3 mm/4.5 mm abutment diameter), and the highest removal value happened with mount #8 after the fifth tapping (420 N, 5.0 mm/5.5 mm). The force to remove IA mounts increased with the number of tappings and with the increase in abutment mass. Three activations (tappings) of the abutment were considered necessary to yield optimal stability, demonstrated by the large increase in removal force.

Triboemission And Wear Of Hydrogenated Carbon Films

1995 ◽  
Vol 409 ◽  
Author(s):  
Keiji Nakayama
Keyword(s):  
Friction Coefficient ◽  
Electron Emission ◽  
Glass Substrate ◽  
Carbon Films ◽  
Lubricating Oil ◽  
Carbon Overcoat ◽  
Dry Air ◽  
Air Atmosphere ◽  
Frictional System ◽  
Frictional Surfaces

AbstractIt is suggested that perfluoropolyether lubricating oil coatings applied to the carbon overcoat film of magnetic recording layers become decomposed by electrons emitted from frictional surfaces. However, no work has at yet been reported as to triboemission of electrons from frictional carbon films.This paper describes the behavior of triboemission of electrons and the friction coefficient during wear of sputtered hydrogenated carbon films (with various hydrogen contents on the glass substrate). The triboemission of electrons, together with friction coeficient, was measured in a frictional system of Al2O3 sliding on carbon films in a reduced dry air atmosphere. The worn surfaces of the carbon films were then observed using both a SEM and an AFM. The results showed that intense triboemission of electrons were observed during wear of hydrogenated carbon films. The electron emission intensity and friction coefficient transit from low to high with hydrogen content in the film. These results are discussed including physical properties of the carbon films such as internal stress and surface wettability.

Tribo-Electromagnetic Phenomena of Hydrogenated Carbon Films—Tribo-Electrons, -Ions, -Photons, and -Charging

1997 ◽  
Vol 119 (4) ◽  
pp. 764-768 ◽  
Author(s):  
Keiji Nakayama ◽  
Benyebka Bou-Said ◽  
Hiroshi Ikeda
Keyword(s):  
Friction Coefficient ◽  
Hydrogen Content ◽  
Emission Intensity ◽  
Charged Particles ◽  
Ambient Air ◽  
Carbon Films ◽  
Frictional Contacts ◽  
Plasma State ◽  
Frictional System ◽  
Positively Charged

Triboemission of negatively charged particles and positively charged particles, tribo-charging and friction coefficient were measured simultaneously using a frictional system with diamond sliding on hydrogenated carbon films in ambient air. The hydrogen content of the carbon films varied from 0 to 43 at. percent. All the carbon films tested emitted both negatively and positively charged particles during sliding. For films with hydrogen content of from 0 to 15 at. percent, neither tribo-charging nor tribo-photons were observed; beyond 15 at. percent hydrogen content, tribo-charging and tribo-photons were observed. With increasing hydrogen content, the emission intensity of the negatively and positively charged particles, photons and tribo-charging increased. It is concluded that a micro-plasma state is formed at the frictional contacts of diamonds sliding on hydrogenated carbon films.

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