Closure to “Discussion of ‘The Statistical Application of a Thermal EHL Theory for Individual Asperity-Asperity Collisions to the Sliding Contact of Rough Surfaces’” (1975, ASME J. Lubr. Technol., 97, p. 319)

1975 ◽  
Vol 97 (2) ◽  
pp. 319-320
Author(s):  
P. E. Fowles
Keyword(s):  
Rough Surfaces ◽  
Sliding Contact ◽  
Statistical Application ◽  
Thermal Ehl

The Statistical Application of a Thermal EHL Theory for Individual Asperity-Asperity Collisions to the Sliding Contact of Rough Surfaces

1975 ◽  
Vol 97 (2) ◽  
pp. 311-318 ◽  
Author(s):  
P. E. Fowles
Keyword(s):  
Friction Coefficient ◽  
Hydrodynamic Lubrication ◽  
Sliding Contact ◽  
Unit Load ◽  
Lubrication Regime ◽  
Statistical Application ◽  
Model Surfaces ◽  
Mixed Lubrication Regime ◽  
Thermal Ehl ◽  
20 Nm

The numerical results of a previously developed thermal EHL theory describing the collisions between idealized asperities are analyzed statistically to obtain macroscopic values of unit load, traction, and friction coefficient for two model surfaces in sliding contact under a range of conditions. It is shown that significant unit loads and tractions can be generated as a result of the microsopic EHL contacts alone. The variation of friction coefficient with load and sliding speed corresponds qualitatively with experiment in the mixed lubrication regime between boundary and hydrodynamic lubrication, but quantitatively the friction coefficients are two to three times too high. The results imply that the lubricant becomes non-Newtonian and/or exhibits a limiting shear strength in virtually all asperity interactions, even those in which the thickness of the intervening lubricant film is maintained in the 20-nm range.

scholarly journals A crystal plasticity assessment of normally-loaded sliding contact in rough surfaces and galling

2018 ◽  
Vol 121 ◽  
pp. 517-542 ◽  
Author(s):  
Bartosz Barzdajn ◽  
Anthony T. Paxton ◽  
David Stewart ◽  
Fionn P.E. Dunne
Keyword(s):  
Crystal Plasticity ◽  
Rough Surfaces ◽  
Sliding Contact

Novel Friction Test Structures for Microelectromechanical Systems

2006 ◽  
Author(s):  
Luke J. Currano ◽  
Miao Yu ◽  
Balakumar Balachandran
Keyword(s):  
Steady State ◽  
Friction Coefficient ◽  
Smooth Surface ◽  
Microelectromechanical Systems ◽  
Rough Surfaces ◽  
Sliding Contact ◽  
Silicon Surfaces ◽  
Mems Devices ◽  
Friction Test ◽  
Friction Measurements

Novel friction test structures that are suitable for determining the friction coefficient of vertical surfaces in microelectromechanical systems (MEMS) devices are fabricated and used to carry out friction measurements on smooth and rough deep reactive ion etched (DRIE) silicon surfaces. The results obtained for rough surfaces show that the friction coefficient decreases as the sliding contact is put through the first eight to ten cycles, before it reaches a steady-state value that closely matches the friction coefficient of the smooth surface.

Friction Heat Due to Sliding of Rough Surfaces: Micro-Scale Interactions and Their Macro-Scale Effect

2008 ◽  
Author(s):  
K. Farhang ◽  
A. Elhomani
Keyword(s):  
Closed Form ◽  
Heat Generation ◽  
Rough Surfaces ◽  
Integral Form ◽  
Sliding Contact ◽  
Heat Generation Rate ◽  
Friction Heat ◽  
Single Asperity ◽  
Macro Scale ◽  
Statistical Integral

When two rough surfaces are in sliding contact an asperity on a surface would experience intermittent temperature flashes as it comes in momentary contact with asperities on a second surface. The frequency of the flash temperatures, their strength and duration depend, in addition to the sliding speed, on the topology of the two surfaces. In this paper a model is developed for the work-heat relation with a consideration of the above-mentioned intermittent nature of contact. The work of friction on one asperity is derived in integral form and closed-form equations. The rate of generation of heat is found due to a single asperity. Using the statistical account of asperity friction heat generation, rate of heat generation between two rough surfaces is obtained both in statistical integral form and in the approximate closed form.

The Effect of Interaction Between Neighboring Asperity Contacts on Wear Mode Transition in Sliding Contact of Rough Surfaces

2005 ◽  
Author(s):  
Tomohisa Tanaka ◽  
Chikara Yamanaka ◽  
Keiji Kyogoku ◽  
Tsunamitsu Nakahara
Keyword(s):  
Rough Surfaces ◽  
Sliding Contact ◽  
Contact Boundary ◽  
Mode Transition ◽  
Relative Slip ◽  
Yielding Condition ◽  
Asperity Contacts ◽  
Wear Mode ◽  
The Difference

Concerning the final aim, that is to make clear the mechanism of the wear mode transition from mild to severe belong to the increase of contact pressure in adhesive wear, estimation of the yielding condition in subsurface under contact boundary between rough surfaces was attempted in this study. Especially the effects of interaction between neighboring contacts as well as relative sliding on the yielding area were focused. The contacts between asperities were modeled by the contact between two neighboring hard wedges with the parallel axes and soft plane to be simplified. These models were calculated by commercial FEM solver in 2-dimension. Additionally, the effect of the difference between the heights of two wedges on the yielding region was evaluated by comparing the result with that obtained from the simple model of two wedges with the same height in non-sliding contact. The results showed that the effect of the interaction between adjacent contacts and existence of relative slip motion give significant factors to the yielding state, on the other hand, the height difference between neighboring asperities affects little the determination of the yielding region.

A three-dimensional fusion prediction model for fractal rough surfaces in the sliding contact process

2014 ◽  
Vol 66 (3) ◽  
pp. 459-467
Author(s):  
Yan Lu ◽  
Zuomin Liu
Keyword(s):  
Temperature Rise ◽  
Rough Surfaces ◽  
Normal Load ◽  
Contact Process ◽  
Three Dimensional ◽  
Contact Problems ◽  
Sliding Contact ◽  
Content Type ◽  
Solution Methods ◽  
Account Temperature

Purpose – The purpose of this manuscript is to analyze the fusion micro-zone generated by typical rough surfaces and investigate the factors of thermal effects on the tribological performance of surface asperities and its results verified by the experiment. Design/methodology/approach – A three-dimensional fractal rough surfaces sliding contact model has been developed, which takes into account temperature rise and distribution. The finite-element method, Green's function method, thermal conduct theory and contact mechanics are used as the solution methods. Findings – The results yield insights into the effects of the sliding velocity, thermal properties of the material, normal load and surface roughness on the temperature rise of the sliding contact surface. It allows the specification of working conductions' properties to reduce fusion. Originality/value – The model is developed and described by using the features of the contact between one flat surface and one rough surface with varied topographies. It can be easily applied for solving the sliding contact problems with different working conditions and specified for designing the surface accuracy in the severe working condition.

Effects of Angular Motion on Planar Rough Surfaces Contact From Static to Sliding

2010 ◽  
Author(s):  
Ting Ni ◽  
Xi Shi
Keyword(s):  
Friction Coefficient ◽  
Rough Surfaces ◽  
Angular Displacement ◽  
Sliding Contact ◽  
Sliding Speed ◽  
Interfacial Forces ◽  
The Stability ◽  
Inclined Angle ◽  
Rough Surface Contact ◽  
Turn Over

Due to the friction moment, there is an angular displacement when two flat rough surfaces come to sliding contact or quasi sliding contact. A 2-DOF inclined rough surface contact model is presented in this work, and the effects of the angular displacement on the friction coefficient, interfacial forces and moments are investigated. The numerical simulations show that both interfacial forces and moments increase with the increasing inclined angle, while the friction coefficient decreases instead. In addition, for a given sliding mass block system, the effects of the friction coefficient and the base sliding speed on the stability of the sliding contact are also discussed. The simulations indicate that a larger friction coefficient and a higher base sliding speed tend to turn over the mass block during the sliding.

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