scholarly journals Contact Mechanics of Rough Surfaces in Hermetic Sealing Studies

2018 ◽  
Author(s):  
Peter Ogar ◽  
Sergey Belokobylsky ◽  
Denis Gorokhov
Keyword(s):  
Contact Mechanics ◽  
Rough Surfaces ◽  
Hermetic Sealing

Numerical Method of Analyzing Contact Mechanics between a Sphere and a Flat Considering Lennard-Jones Surface Forces of Contacting Asperities and Noncontacting Rough Surfaces

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
Kyosuke Ono
Keyword(s):  
Numerical Method ◽  
Contact Mechanics ◽  
Rough Surfaces ◽  
Present Theory ◽  
Adhesive Contact ◽  
Adhesive Force ◽  
Surface Forces ◽  
Contact Theory ◽  
Magnetic Disk ◽  
Lennard Jones

A new numerical method of analyzing adhesive contact mechanics between a sphere and a flat with sub-nanometer roughness is presented. In contrast to conventional theories, the elastic deformations of mean height surfaces and contacting asperities, and Lennard-Jones (LJ) surface forces of both the contacting asperities and noncontacting rough surfaces including valley areas are taken into account. Calculated contact characteristics of a 2-mm-radius glass slider contacting a magnetic disk with a relatively rough surface and a 30-mm-radius head slider contacting a currently available magnetic disk with lower roughness are shown in comparison with conventional adhesive contact theories. The present theory was found to give a larger adhesive force than the conventional theories and to converge to a smooth sphere-flat contact theory as the roughness height approaches zero.

scholarly journals A multi-scale FEM-BEM formulation for contact mechanics between rough surfaces

2019 ◽  
Vol 65 (3) ◽  
pp. 731-749
Author(s):  
Jacopo Bonari ◽  
Maria R. Marulli ◽  
Nora Hagmeyer ◽  
Matthias Mayr ◽  
Alexander Popp ◽  
...  
Keyword(s):  
Contact Mechanics ◽  
Rough Surfaces ◽  
Multi Scale

Parametric Study of Simulated Randomly Rough Surfaces Used in Contact Mechanics

2019 ◽  
pp. 162-168
Author(s):  
Rafael Schouwenaars ◽  
Miguel Ángel Ramírez ◽  
Carlos Gabriel Figueroa ◽  
Víctor Hugo Jacobo ◽  
Armando Ortiz Prado
Keyword(s):  
Contact Mechanics ◽  
Parametric Study ◽  
Rough Surfaces ◽  
Randomly Rough Surfaces

Exact Spectral Moments and Differentiability of the Weierstrass-Mandelbrot Fractal Function

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Itzhak Green
Keyword(s):  
Contact Mechanics ◽  
Rough Surfaces ◽  
Numerical Procedure ◽  
Mathematical Expression ◽  
Computational Effort ◽  
Mathematical Treatment ◽  
Real Surface ◽  
Fractal Function ◽  
Spectral Moments ◽  
Closed Form Solutions

Abstract Fractal mathematics using the Weierstrass-Mandelbrot (WM) function has spread to many fields of science and engineering. One of these is the fractal characterization of rough surfaces, which has gained ample acceptance in the area of contact mechanics. That is, a single mathematical expression (the WM function) contains characteristics that mimic the appearance of roughness. Moreover, the “roughness” is “similar” across large dimension scales ranging from macro to nano. The field of contact mechanics is largely divided into two schools of thought: (1) the roughness of real surfaces is essentially random, for which stochastic treatment is appropriate, and (2) surface roughness can be reduced to fractal mathematics using fractal parameters. Under certain mathematical constraints, the WM function is either stochastic or deterministic. The latter has the appeal that it contains no randomness, so fractal mathematics may offer closed-form solutions. Spectral moments of rough surfaces still apply to both approaches, as these represent physical metrology properties of the surface standard deviation, slope, and curvature. In essence, spectral moments provide a means of data reduction so that other physical processes can subsequently be applied. It is well known, for example, that the contact model of rough surfaces, by Greenwood and Williamson (GW), depends on parameters that are direct outcomes of these moments. Despite the vast amount of publications on the WM function dedicated to surfaces, two papers stand out as originators, where the others mostly rework their results. These two papers, however, contain some omissions and approximations that may lead to gross errors in the estimation of the spectral moments. The current work revisits these papers and adds information, but departs in the mathematical treatment to derive exact expressions for the said moments. Moreover, it is said that the WM function is nondifferential. That is also revisited herein, as another approach to derive the spectral moments depends on such derivatives. First, the complete mathematical treatment of the WM function is made, then the spectral moments are derived to yield exact forms, and finally, examples are given where the physical meanings of the approximate and exact moments are discussed and their values are compared. Numerical procedures will be introduced for both, and the effectiveness of the computational effort is discussed. One numerical procedure is particularly effective for any digitized signal, whether that originates from analytical functions (e.g., WM) or real surface measurements.

Effects of Lattice Orientation and Size on Molecular Asperity Contact Models

2009 ◽  
Author(s):  
J. Robert Polchow ◽  
Wei Huang ◽  
Robert L. Jackson
Keyword(s):  
Contact Mechanics ◽  
Molecular Model ◽  
Rough Surfaces ◽  
Minimum Size ◽  
Small Scale ◽  
Asperity Contact ◽  
Lattice Orientation ◽  
Noticeable Effect ◽  
Contact Models ◽  
Number Of Particles

Surface asperities can range widely in size. Therefore it is important to characterize the effect of size and scale on the contact mechanics. This work presents a molecular model of asperity contact in order to characterize small scale asperity contact. The effects of lattice orientation and radius (number of particles) are examined. It appears that lattice orientation has a noticeable effect, but nominally may not be important in the contact of asperities and rough surfaces. The size appears to be important until a certain minimum size is achieved.

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