scholarly journals Modeling of the Loading–Unloading Contact of Two Cylindrical Rough Surfaces with Friction

2020 ◽  
Vol 10 (3) ◽  
pp. 742 ◽  
Author(s):  
Honghai Wang ◽  
Peng Jia ◽  
Liquan Wang ◽  
Feihong Yun ◽  
Gang Wang ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Contact Area ◽  
Fractal Model ◽  
Contact Load ◽  
Real Contact Area ◽  
Curvature Radius ◽  
Real Contact ◽  
Deformation Stages ◽  
Nonlinear Relation ◽  
Loading And Unloading

The first fractal model for the loading–unloading process between two cylindrical surfaces with friction is presented. The nonlinear relation between the real contact area and the contact load in different deformation stages are deduced for a load–unload cycle. The impacts of parameters in the model are discussed. The numerical results show that for a given dimensionless contact load, the dimensionless real contact area of the loading–unloading process of cylindrical contact surface with friction, as well as the differences of the dimensionless real contact area between the loading and unloading processes, increase with the increase of the loading interference and fractal dimension, decrease of the profile scaling parameter and curvature radius, or the substitution of external contact for internal contact.

A Fractal Theory of the Temperature Distribution at Elastic Contacts of Fast Sliding Surfaces

1995 ◽  
Vol 117 (2) ◽  
pp. 203-214 ◽  
Author(s):  
S. Wang ◽  
K. Komvopoulos
Keyword(s):  
Fractal Dimension ◽  
Temperature Distribution ◽  
Contact Area ◽  
Temperature Rise ◽  
Maximum Temperature ◽  
Real Contact Area ◽  
The Real ◽  
Sliding Surfaces ◽  
Real Contact ◽  
Maximum Temperature Rise

The statistical temperature distribution at fast sliding interfaces is studied by characterizing the surfaces as fractals and considering elastic deformation of the asperities. The fractions of the real contact area in the slow, transitional, and fast sliding regimes are determined based on the microcontact size distribution. For a smooth surface in contact with a rough surface, the temperature rises at the real contact area are determined under the assumption that most of the frictional heat is transferred to one of the surfaces. The interfacial temperature rises are bounded by the maximum temperature rise at the largest microcontact when the fractal dimension is 1.5 or less, and are unbounded when it is greater than 1.5. Higher temperature rises occur at larger microcontacts when the fractal dimension is less than 1.5, and at smaller microcontacts when it is greater than 1.5. For a fractal dimension of 1.5, the maximum temperature rise at a microcontact is independent of its size. The maximum temperature rise at the largest microcontact is expressed as a function of the friction coefficient, sliding speed, elastic and thermal properties, real and apparent contact areas, and fractal parameters. The closed-form solutions for the distribution density function of the temperature rise can be used to calculate the fraction of the real contact area of fast sliding surfaces subjected to temperature rises in any given range. The present theory is applied to boundary-lubricated and dry sliding contacts to determine the fractions of the real contact area where lubricant degradation and thermal surface failure may occur.

scholarly journals An experimental study on the relation between friction force and real contact area

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
X. M. Liang ◽  
Y. Z. Xing ◽  
L. T. Li ◽  
W. K. Yuan ◽  
G. F. Wang
Keyword(s):  
Experimental Study ◽  
Friction Force ◽  
Contact Area ◽  
Linear Relation ◽  
Normal Load ◽  
Real Contact Area ◽  
Normal Loading ◽  
Real Contact ◽  
Loading And Unloading ◽  
Nominal Contact Area

AbstractClassical laws of friction suggest that friction force is proportional to the normal load and independent of the nominal contact area. As a great improvement in this subject, it is now widely accepted that friction force is proportional to the real contact area, and much work has been conducted based on this hypothesis. In present study, this hypothesis will be carefully revisited by measuring the friction force and real contact area in-site and real-time at both normal loading and unloading stages. Our experiments reveal that the linear relation always holds between friction force and normal load. However, for the relation between friction force and real contact area, the linearity holds only at the loading stage while fails at the unloading stage. This study may improve our understanding of the origin of friction.

Numerical Simulation for the Interaction of the Semi-Fixed Abrasive Plate with the Workpiece

2011 ◽  
Vol 305 ◽  
pp. 107-111
Author(s):  
Ying Zhang ◽  
Zhao Zhong Zhou ◽  
Ju Long Yuan ◽  
Chong Da Lu
Keyword(s):  
Contact Area ◽  
Contact Load ◽  
Process Efficiency ◽  
Real Contact Area ◽  
Processing Parameter ◽  
The Real ◽  
Real Contact ◽  
Key Factor ◽  
Abrasive Surface ◽  
Fixed Abrasive

In order to improve the efficiency of ultra-precision processing, the semi-fixed abrasive plate (SFAP) is developed to reduce or eliminate the surface and subsurface defects and improve the process efficiency. The interaction of the semi-fixed abrasive plate-workpiece is the key factor for the processing. The complex plate-workpiece interaction is taken into consideration in the generation of the semi-fixed abrasive surface in this paper. A numerical model which allows describing the elastic-plastic contact load of the isotropic fractal surface and the real contact area of plate-workpiece is developed for the semi-fixed abrasive plate. The results shows that the real contact area is only a part of the workpiece and it changed with the contact load alteration, it is useful to determine the processing parameter of SFAP lapping.

scholarly journals Does Linearity Always Hold between Friction Force and Real Contact Area: An Experimental Study

2021 ◽  
Author(s):  
Xuan Ming Liang ◽  
Yuzhe Xing ◽  
Leitao Li ◽  
Weike Yuan ◽  
G.F. Wang
Keyword(s):  
Experimental Study ◽  
Friction Force ◽  
Contact Area ◽  
Normal Load ◽  
Real Contact Area ◽  
Normal Loading ◽  
Real Contact ◽  
Loading And Unloading ◽  
Nominal Contact Area ◽  
Real Area

Classical laws of friction suggest that friction force is proportional to the normal load and independent of the nominal contact area. As a great improvement in this subject, it is now widely accepted that friction force is proportional to the real area in contact, and much work has been conducted based on this hypothesis. In present study, this hypothesis will be carefully revisited by measuring the friction force and real contact area in-site and real-time at both normal loading and unloading stages. Our experiments reveal that the linear relation always holds between friction force and normal load. However, for the relation between friction force and real contact area, the linearity holds only at the loading stage while fails at the unloading stage. This study may improve our understanding of the origin of friction.

An Analytical Thermodynamic Approach to Friction of Rubber on Ice

2012 ◽  
Vol 40 (2) ◽  
pp. 124-150
Author(s):  
Klaus Wiese ◽  
Thiemo M. Kessel ◽  
Reinhard Mundl ◽  
Burkhard Wies
Keyword(s):  
Coefficient Of Friction ◽  
Liquid Layer ◽  
Contact Area ◽  
Leading Edge ◽  
Viscous Friction ◽  
Analytical Approximation ◽  
Real Contact Area ◽  
Length Scales ◽  
Real Contact ◽  
Ice Surface

ABSTRACT The presented investigation is motivated by the need for performance improvement in winter tires, based on the idea of innovative “functional” surfaces. Current tread design features focus on macroscopic length scales. The potential of microscopic surface effects for friction on wintery roads has not been considered extensively yet. We limit our considerations to length scales for which rubber is rough, in contrast to a perfectly smooth ice surface. Therefore we assume that the only source of frictional forces is the viscosity of a sheared intermediate thin liquid layer of melted ice. Rubber hysteresis and adhesion effects are considered to be negligible. The height of the liquid layer is driven by an equilibrium between the heat built up by viscous friction, energy consumption for phase transition between ice and water, and heat flow into the cold underlying ice. In addition, the microscopic “squeeze-out” phenomena of melted water resulting from rubber asperities are also taken into consideration. The size and microscopic real contact area of these asperities are derived from roughness parameters of the free rubber surface using Greenwood-Williamson contact theory and compared with the measured real contact area. The derived one-dimensional differential equation for the height of an averaged liquid layer is solved for stationary sliding by a piecewise analytical approximation. The frictional shear forces are deduced and integrated over the whole macroscopic contact area to result in a global coefficient of friction. The boundary condition at the leading edge of the contact area is prescribed by the height of a “quasi-liquid layer,” which already exists on the “free” ice surface. It turns out that this approach meets the measured coefficient of friction in the laboratory. More precisely, the calculated dependencies of the friction coefficient on ice temperature, sliding speed, and contact pressure are confirmed by measurements of a simple rubber block sample on artificial ice in the laboratory.

scholarly journals Relationship between the real contact behavior and tribological characteristics of cotton fabric

Friction ◽  
2020 ◽  
Author(s):  
Rongxin Chen ◽  
Jiaxin Ye ◽  
Wei Zhang ◽  
Jiang Wei ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Contact Area ◽  
Dynamic Change ◽  
Tribological Characteristics ◽  
Real Contact Area ◽  
Cotton Fibers ◽  
Friction Behavior ◽  
Contact Behavior ◽  
The Real ◽  
Real Contact

Abstract The tribological characteristics of cotton fibers play an important role in engineering and materials science, and real contact behavior is a significant aspect in the friction behavior of cotton fibers. In this study, the tribological characteristics of cotton fibers and their relationship with the real contact behavior are investigated through reciprocating linear tribotesting and real contact analysis. Results show that the friction coefficient decreases with a general increase in load or velocity, and the load and velocity exhibit a co-influence on the friction coefficient. The dynamic change in the real contact area is recorded clearly during the experiments and corresponds to the fluctuations observed in the friction coefficient. Moreover, the friction coefficient is positively correlated with the real contact area based on a quantitative analysis of the evolution of friction behavior and the real contact area at different loads and velocities. This correlation is evident at low velocities and medium load.

scholarly journals Estimation of real contact area during sliding friction from interface temperature

AIP Advances ◽  
2016 ◽  
Vol 6 (6) ◽  
pp. 065227
Author(s):  
Sung Keun Chey ◽  
Pengyi Tian ◽  
Yu Tian
Keyword(s):  
Contact Area ◽  
Sliding Friction ◽  
Real Contact Area ◽  
Interface Temperature ◽  
Real Contact

An Observation Method of Real Contact Area during PVA Brush Scrubbing

2018 ◽  
Vol 282 ◽  
pp. 73-76 ◽  
Author(s):  
Toshiyuki Sanada ◽  
Masanao Hanai ◽  
Akira Fukunaga ◽  
Hirokuni Hiyama
Keyword(s):  
Contact Area ◽  
Contact Condition ◽  
Real Contact Area ◽  
Led Light ◽  
The Real ◽  
Real Contact ◽  
Observation Method

In the post CMP cleaning, the contact condition between PVA brush and surface is very important. In this study, we observed the real contact area between a brush and surface using a collimating LED light and prism. As a result, we found that the real contact area increases with increasing the brush compression. In addition, we also found that the real contact area decreases when the brush starts to move, and the brush was locally compressed due to its deformation.

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