Effect of surface roughness topography on percolation characteristic of contact interface

2020 ◽  
pp. 135065012097735
Author(s):  
Tong Zhang ◽  
Xiaojun Liu ◽  
Yan Zhang ◽  
Jiaxin Ye ◽  
Wei Wang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Percolation Threshold ◽  
Critical Pressure ◽  
Rough Surfaces ◽  
Glass Plate ◽  
Peak Height ◽  
Elastic Contact ◽  
Contact Interface ◽  
Autocorrelation Length ◽  
Effect Of Surface

The contact geometry of rough surfaces markedly affects the functional properties such as sealing and lubrication. The effect of surface roughness on the percolation characteristic of elastic contact was studied. The elastic contact of randomly rough surfaces with a glass plate was performed using four different surface roughnesses of silicone rubber blocks as specimens. The results illustrate that the percolation threshold was significantly affected by the valley morphology of a surface. The increase in depth and void volume of valleys improved the connectivity between valleys, but impeded the coalescence of contact clusters, resulting in the extinction of the spanning void cluster allowing fluid flow when the relative contact area was large. Furthermore, the critical pressure and connectivity at the percolation threshold were related to the maximum peak height and autocorrelation length of a surface, respectively.

Effect of Surface Roughness on Adhesion and Friction of Microfibers in Side Contact

2008 ◽  
Author(s):  
Mircea Teodorescu ◽  
Carmel Majidi ◽  
Homer Rahnejat ◽  
Ronald S. Fearing
Keyword(s):  
Mathematical Model ◽  
Surface Roughness ◽  
Closed Form ◽  
Contact Mechanics ◽  
Elastic Contact ◽  
Linear Elastic ◽  
Multi Scale ◽  
Analytic Approximations ◽  
Effect Of Surface

A multi-scale mathematical model is used to study the effect of surface roughness on the adhesion and friction of microfibers engaged in side contact. Results are compared to closed-form analytic approximations derived from linear elastic contact mechanics.

Effect of the finite size of generated rough surfaces on the percolation threshold

2019 ◽  
Vol 233 (16) ◽  
pp. 5897-5902 ◽  
Author(s):  
Zhimeng Yang ◽  
Xiaoyu Ding ◽  
Jianhua Liu ◽  
Feikai Zhang
Keyword(s):  
Percolation Threshold ◽  
Rough Surfaces ◽  
Finite Size ◽  
Sampling Interval ◽  
Search Method ◽  
Transform Method ◽  
Sealing Performance ◽  
Fast Fourier Transform Method ◽  
Numerical Generation ◽  
Autocorrelation Length

Percolation threshold is a very important parameter to estimate the sealing performance. Thus, it is crucial to determine the correct value of the percolation threshold for contact sealing surfaces. In this paper, we applied a numerical generation method, in which the autocorrelation length can be easily controlled, to obtain different Gaussian isotropic rough surfaces. Then, the contact status between a rigid flat half-space and numerically generated rough surfaces were calculated using the conjugate gradient-fast Fourier transform method. Based on the contact status, the percolation threshold was obtained using a search method. The calculated results established that the percolation threshold of [Formula: see text] is determined for Gaussian isotropic contacting rough surfaces. To obtain an exact value of the percolation threshold, the finite size of the generated rough surfaces should be six times greater than the autocorrelation length, and the autocorrelation length should not be smaller than 20 times the sampling interval.

Effect of Surface Roughness on Fouling of Calcium Carbonate: An Experimental Investigation

2010 ◽  
Author(s):  
M. Izadi ◽  
D. K. Aidun ◽  
P. Marzocca ◽  
H. Lee
Keyword(s):  
Surface Roughness ◽  
Calcium Carbonate ◽  
Rough Surface ◽  
Smooth Surface ◽  
Rough Surfaces ◽  
Operating Conditions ◽  
Tubular Heat Exchanger ◽  
Analytical Microscopy ◽  
Deposit Layer ◽  
Effect Of Surface

The effect of surface roughness on the fouling behavior of calcium carbonate is experimentally investigated. The real operating conditions of a tubular heat exchanger are simulated by performing prolonged experiments with duration of 3 to 7 days. The solution used is a mixture of sodium bicarbonate and calcium chloride in de-ionized water with the concentration of 0.4 g/l of each. An on-line fouling evaluation system was developed such that the fouling resistance for a selected solution could be measured in real time. The experiments are repeated with the same procedure for 90/10 Cu/Ni tubes with different internal surface roughness. After the experiment the surface is analyzed by analytical microscopy to investigate the morphology of the deposit layer. Comparison of the experimental results of smooth and rough surfaces shows that a combination of aragonite and calcite polymorphs are formed on rough surface while only dendritic porous aragonite crystals are formed on smooth surface. Accordingly, the deposit layer formed on rough surface is denser and has a higher thermal resistance comparing to that formed on smooth surface. The fouling factor-time curves of smooth and rough surfaces obtained by the current experimental study agree with the results found by the analytical microscopy of the surface and show higher fouling resistances for rough surface. Experimental data is significantly important for the design, and formulating operating, and cleaning schedules of the equipment.

The Effect of Surface Roughness in Polymers on X-Ray Fluorescence Intensity Measurements

1967 ◽  
Vol 11 ◽  
pp. 177-184
Author(s):  
J. Gianelos ◽  
C. E. Wilkes
Keyword(s):  
Surface Roughness ◽  
Matrix Effects ◽  
Rough Surfaces ◽  
Target Material ◽  
Wire Mesh ◽  
Coarse Mesh ◽  
X Ray ◽  
Intensity Measurements ◽  
Intensity Changes ◽  
Effect Of Surface

AbstractWe sought to determine how seriously surface roughness affects X-ray intensity measurements in polymers. Fourteen elements ranging from lead to silicon were added singly to fourteen batches of trans-1,4-polyisoprene. Smooth pressings of each batch were made, and intensity readings were taken (I0). Reproducibly rough surfaces were made from these by molding a square wire-mesh pattern into them, with the use of Tyler standard sieve screens. The amount of roughness was controlled by using screens of very fine to very coarse mesh. We studied the change in the X-ray intensity of the rough surfaces versus the smooth [(I/I0) × 100] with respect to: (1) the degree of roughness, (2) concentration of the added element, (3) emitted wavelength of the added element, (4) X-ray tube target material, and (5) correction for matrix effects on the intensity. We found that, at wavelengths emitted below 1 Å, intensity differences are small, regardless of which factors were varied. At wavelengths emitted above 1 Å, however, we found large differences. The intensity changes are highly dependent on roughness. Also, they become greater at the longer emitted wavelengths and with increasing concentration of added elements. Beginning with Ti Kα, losses are much higher with the use of chromium primary radiation than with tungsten. A technique of milling polyethylene into polymers with rough surfaces to provide a smooth surface is discussed.

Effect of Surface Roughness on the Adhesion of Elastomers to Hard Surfaces

2010 ◽  
Vol 662 ◽  
pp. 39-51 ◽  
Author(s):  
Keith Fuller
Keyword(s):  
Surface Roughness ◽  
Rough Surfaces ◽  
Theoretical Work ◽  
Contact System ◽  
Contact Theory ◽  
Smooth Surfaces ◽  
Rigid Substrate ◽  
Recent Theoretical Work ◽  
Effect Of Surface

The work presented started with the aim of trying to explain why clean smooth surfaces of materials such as metals brought gently into contact show no adhesion. The observation by Johnson Kendall & Roberts of adhesion between smooth surfaces of an elastomeric hemisphere and a rigid substrate suggested a model contact system with which the effect of surface roughness could be investigated experimentally. Moreover the Johnson-Kendal-Roberts (JKR) contact theory could be used to predict the effect of roughness on adhesion. The observations and predictions obtained are compared, and the implications for the contact of two rigid materials outlined. The limitations of the validity of the predictions are mentioned. Further studies of the adhesion to rough surfaces, in particular the phenomenon of enhanced adhesion at low roughness, will be discussed. Finally, more recent theoretical work is briefly referred to.

scholarly journals Deterministic normal contact of rough surfaces with adhesion using a surface integral method

2020 ◽  
Vol 476 (2242) ◽  
pp. 20200281 ◽  
Author(s):  
Ali Ghanbarzadeh ◽  
Mostafa Faraji ◽  
Anne Neville
Keyword(s):  
Surface Roughness ◽  
Root Mean Square ◽  
Fundamental Problem ◽  
Rough Surfaces ◽  
Adhesive Contact ◽  
Mean Square ◽  
Surface Integral ◽  
Normal Contact ◽  
Surface Integration ◽  
Effect Of Surface

The fundamental problem of adhesion in the presence of surface roughness and its effect on the prediction of friction has been a hot topic for decades in numerous areas of science and engineering, attracting even more attention in recent years in areas such as geotechnics and tectonics, nanotechnology, high-value manufacturing and biomechanics. In this paper a new model for deterministic calculation of the contact mechanics for rough surfaces in the presence of adhesion is presented. The contact solver is an in-house boundary element method that incorporates fast Fourier transform for numerical efficiency. The adhesive contact model considers full Lennard-Jones potentials and surface integration at the asperity level and is validated against models in the literature. Finally, the effect of surface roughness on the adhesion between surfaces was studied, and it was shown that the root mean square gradient of surface roughness can change the adhesive pressures irrespective of the root mean square surface roughness. We have tested two adhesion parameters based on Johnson's modified criteria and Ciavarella's model. We showed that Civarella's model introduces the most reasonable criteria suggesting that the RMS roughness and large wavelength of surfaces roughness are the important parameters of adhesion between rough surfaces.

Surface Roughness Effects in Infinitely Long Porous Journal Bearings

1999 ◽  
Vol 121 (1) ◽  
pp. 139-147 ◽  
Author(s):  
K. Gururajan ◽  
J. Prakash
Keyword(s):  
Surface Roughness ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Rough Surfaces ◽  
Stochastic Theory ◽  
Journal Bearings ◽  
Roughness Effects ◽  
Effect Of Surface

Christensen’s stochastic theory of hydrodynamic lubrication of rough surfaces is used to study the effect of surface roughness in an infinitely long porous journal bearing operating under steady conditions. It is shown that the surface roughness considerably influences the bearing performance; the direction of the influence depends on the roughness type.

Molecular investigation of the wettability of rough surfaces using molecular dynamics simulation

2018 ◽  
Vol 20 (34) ◽  
pp. 22308-22319 ◽  
Author(s):  
Hamzeh Yaghoubi ◽  
Masumeh Foroutan
Keyword(s):  
Molecular Dynamics ◽  
Surface Roughness ◽  
Molecular Dynamics Simulation ◽  
Rough Surfaces ◽  
Dynamics Simulation ◽  
Computational Investigation ◽  
Molecular Investigation ◽  
Effect Of Surface

In the present study, a computational investigation on the effect of surface roughness on the wettability behavior of water nanodroplets has been performed via molecular dynamics simulation.

Correlation of Scuffing Experiments With EHL Analysis of Rough Surfaces

1991 ◽  
Vol 113 (2) ◽  
pp. 318-326 ◽  
Author(s):  
S. C. Lee ◽  
H. S. Cheng
Keyword(s):  
Experimental Data ◽  
Surface Roughness ◽  
Rough Surfaces ◽  
Elastohydrodynamic Lubrication ◽  
Mineral Oil ◽  
Line Contact ◽  
Lubrication Film ◽  
Surface Profiles ◽  
Effect Of Surface ◽  
Ehl Contact

Scuffing experiments were conducted on a twin disk machine using straight mineral oil. The purpose of these experiments was to validate some existing scuffing theories based on the breakdown of lubrication film in concentrated partial ehl (elastohydrodynamic lubrication) contacts. The verify these scuffing theories, a model for solving the complete inlet half ehl solution to the line contact between two rough longitudinally ground surfaces was developed. This ehl contact model was based on a newly developed concept, “average gap.” The effect of surface roughness on lubrication was taken into account by simulating the contacts between many different pairs of rough surfaces. In order to solve for the ehl contact solutions of the two disks under scuffing conditions, the actual run-in surface profiles of the mating disks, digitized just prior to failure, were used. Finally the correlations were made between the scuffing theory and the experimental data.

The Effects of Surface Roughness and Topography on the Contact Behavior of Elastic Bodies

1994 ◽  
Vol 116 (4) ◽  
pp. 804-810 ◽  
Author(s):  
Ning Ren ◽  
Si C. Lee
Keyword(s):  
Surface Roughness ◽  
Root Mean Square Roughness ◽  
Asperity Contact ◽  
Performance Variables ◽  
Elastic Bodies ◽  
Real Area Of Contact ◽  
Wide Range ◽  
Autocorrelation Length ◽  
Mathematical Relationships ◽  
Effect Of Surface

The real area of contact, average gap, and mean asperity contact pressure are important variables for understanding friction, wear, and lubrication in contacting systems. They are known as “performance variables.” Contact simulations were conducted for a wide range of surface topographies and an extensive amount of information was generated. Using this information, the performance variables were curve fitted and convenient mathematical relationships were formulated. The surfaces used in the simulations were numerically generated and they varied widely in statistical roughness properties, ranging from isotropic to strongly anisotropic. The effect of surface roughness on the performance variables were studied using three parameters—composite Root Mean Square roughness (σ), autocorrelation length (λx*), and asperity aspect ratio (γ).

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