A Fractal Theory of the Interfacial Temperature Distribution in the Slow Sliding Regime: Part II—Multiple Domains, Elastoplastic Contacts and Applications

1994 ◽  
Vol 116 (4) ◽  
pp. 824-832 ◽  
Author(s):  
S. Wang ◽  
K. Komvopoulos
Keyword(s):  
Temperature Distribution ◽  
Contact Area ◽  
Temperature Rise ◽  
Frictional Heating ◽  
Fractal Theory ◽  
Cumulative Distribution ◽  
Maximum Temperature ◽  
Real Contact Area ◽  
Fractal Structures ◽  
Real Contact

The limitation of the fractal theory as applied to real surfaces is interpreted, and engineering surfaces are considered as a superimposition of fractal structures on macroscopic regular shapes by introducing the concepts of fractal-regular surfaces and multiple fractal domains. The effects of frictional heating at neighboring microcontacts are analyzed, and a simple solution of the temperature distribution is obtained for contact regions that are appreciably larger than a fractal domain. It is shown that the temperature rise at an elastoplastic microcontact does not differ significantly from that at an elastic microcontact of a similar geometry under the same load. The fractional real contact area subjected to temperature rises greater than any given value is represented by a complementary cumulative distribution function. The analysis yields that the average value and standard deviation of the temperature rise at the real contact area are 0.4 and 0.24 times the maximum temperature rise, respectively. The implications of the theory in boundary lubrication are demonstrated in light of results for ceramic materials.

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.

A Fractal Theory of the Interfacial Temperature Distribution in the Slow Sliding Regime: Part I—Elastic Contact and Heat Transfer Analysis

1994 ◽  
Vol 116 (4) ◽  
pp. 812-822 ◽  
Author(s):  
S. Wang ◽  
K. Komvopoulos
Keyword(s):  
Contact Area ◽  
Temperature Rise ◽  
Fractal Theory ◽  
Heat Transfer Analysis ◽  
Maximum Temperature ◽  
Real Contact Area ◽  
The Real ◽  
Real Contact ◽  
Maximum Temperature Rise ◽  
Fractal Domain

The frictional temperature rises at the microcontacts of rough surfaces are analyzed by characterizing the surfaces as fractals and assuming Hertzian contacts of spherical asperity tips. The maximum temperature rise of a fractal surface domain in the slow sliding regime, where transient effects are negligible, is expressed as a function of thermomechanical properties, sliding speed, friction coefficient, real and apparent contact areas of the fractal domain, and fractal parameters. The distribution density function of the temperature rise at the real contact area is also determined based on the statistical temperature rise distributions of individual microcontacts and the maximum temperature rise of a fractal domain. This function characterizes the fractions of the real contact area subjected to different temperature rises, and can be used to analyze tribological interactions on dry and boundary-lubricated sliding surfaces.

scholarly journals Temperature rise of diamond-like carbon during sliding: Consideration of the real contact area

2019 ◽  
Vol 131 ◽  
pp. 496-507 ◽  
Author(s):  
S. Yamamoto ◽  
T. Liskiewicz ◽  
K. Fujimura ◽  
K. Tashiro ◽  
O. Takai
Keyword(s):  
Contact Area ◽  
Temperature Rise ◽  
Real Contact Area ◽  
Diamond Like Carbon ◽  
The Real ◽  
Real Contact

Surface fractal topography-based contact stiffness determination of spindle–toolholder joint

2015 ◽  
Vol 230 (4) ◽  
pp. 602-610 ◽  
Author(s):  
Yongsheng Zhao ◽  
Xiaolei Song ◽  
Ligang Cai ◽  
Zhifeng Liu ◽  
Qiang Cheng
Keyword(s):  
Contact Force ◽  
Contact Area ◽  
High Speed ◽  
Contact Stiffness ◽  
Fractal Theory ◽  
Contact Model ◽  
Real Contact Area ◽  
Real Contact ◽  
Fractal Parameters ◽  
Relationship Of

Accurate modeling of contact stiffness is crucial in predicting the dynamic behavior and chatter vibration of spindle–toolholder system for high-speed machining centers. This paper presents a fractal theory-based contact model of spindle–toolholder joint to obtain the contact stiffness and its real contact area. Topography of the contact surfaces of spindle–toolholder joint is fractal featured and determined by fractal parameters. Asperities in micro-scale are considered as elastic or plastic deformation. Then, the contact stiffness, the real contact area, the elastic contact force, and the plastic contact force of the whole contact surface are calculated by integrating the micro asperities. The relationship of the contact stiffness and the drawbar force follows a power law, in which the power index is determined by the fractal parameters. Experiments are conducted to verify the efficiency of the proposed model. The results from the fractal contact model of spindle–toolholder joint have good agreement with those of experiments.

A multi-scale model of real contact area for linear guideway based on the fractal theory

2021 ◽  
pp. 095440622098336
Author(s):  
Xinxin Li ◽  
Zhimin Li ◽  
Sun Jin ◽  
Jichang Zhang
Keyword(s):  
Contact Area ◽  
Manufacturing Industry ◽  
Fractal Theory ◽  
Scale Model ◽  
Design Stage ◽  
Real Contact Area ◽  
The Real ◽  
Multi Scale ◽  
Real Contact ◽  
Proposed Model

High precision, efficiency and reliability are the unremitting pursuits of machinery manufacturing industry. As one of the pivotal function parts of high-end NC machine tool, precise linear guideway determines the machining precision and operation performance. Accurate evaluation and prediction of surface topography are the crucial effects on the matching performance of linear guideway. In this paper, the real contact area is regarded as a key parameter, a multi-scale method with the fractal theory is proposed. First, the contact area of a single asperity was obtained with Hertz contact theory. Afterwards, the contact area between rough surfaces was deduced by the fractal theory. Finally, using the proposed multi-scale contact mechanics model, the real contact area between rough plane and cylinder was obtained by integral solution. Compared with the former fractal model and GW model, the proposed model on the real contact area calculation of linear guideway is more accurate and comprehensive. The effect factors of load, fractal parameter and friction were discussed, the increasing rate of real contact area of smoother surface is greater as load increases. The proposed model may provide practical guidance for assembly accuracy and surface quality requirements at design stage.

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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