Numerical Method of Analyzing Contact Mechanics Between a Sphere and a Flat Considering Lennard-Jones Surface Forces of Contacting Asperities and Mean Height Surfaces

2010 ◽  
Author(s):  
Kyosuke Ono
Keyword(s):  
Contact Mechanics ◽  
Adhesion Force ◽  
Surface Forces ◽  
Elastic Contact ◽  
Analysis Method ◽  
Elastic Deformations ◽  
Magnetic Disk ◽  
Head Slider ◽  
Lennard Jones ◽  
Relaxation Iteration

A numerical analysis method for elastic contact mechanics between a sphere and a flat with a sub-nanometer roughness is presented by taking account of Lennard-Jones (LJ) surface forces. In contrast to conventional theories, the elastic deformations and LJ surface forces of both mean surfaces and contacting asperities are taken into account. Convergent solutions obtained by a simple under-relaxation iteration method are discussed for 2-mm radius glass slider and 20-mm radius head slider contacting with a magnetic disk. It is found that the increase in adhesion force with a decrease in surface roughness can be suppressed by deceasing asperity radius and increasing asperity density.

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.

Numerical Analysis Method of Contact Mechanics Between a Sphere and a Flat Considering Lennard-Jones Surface Forces of Contacting Asperities and All Rough Height Surfaces

2011 ◽  
Author(s):  
Kyosuke Ono
Keyword(s):  
Numerical Analysis ◽  
Contact Mechanics ◽  
Present Theory ◽  
Adhesive Contact ◽  
Surface Forces ◽  
Asperity Contact ◽  
Analysis Method ◽  
Surface Theory ◽  
Numerical Analysis Method ◽  
Lennard Jones

A new numerical analysis method for elastic adhesive contact mechanics between a sphere and a flat with a sub-nanometer roughness is presented. In contrast to conventional theories, the elastic deformations of both contacting asperities and mean height surface and Lennard-Jones (LJ) surface forces of both contacting asperities and all rough surfaces including valley areas are taken into account New adhesive force of contacting asperity is used from asperity contact analysis. Calculated results for head-disk asperity contact with current low roughness are shown in comparison with conventional theories. The relationship among present theory, mean height surface theory and perfectly smooth surface theory is discussed.

VISCOELASTIC ADHESION OF A SPHERICAL TIP INDENTING A FLAT RIGID SURFACE USING LENNARD-JONES INTERACTION

2015 ◽  
Vol 76 (10) ◽  
Author(s):  
A.K.X. Leong ◽  
W.W.F. Chong
Keyword(s):  
Mathematical Model ◽  
Contact Problem ◽  
Physical Properties ◽  
Contact Problems ◽  
Surface Forces ◽  
Elastic Contact ◽  
Rigid Surface ◽  
Lennard Jones ◽  
Viscoelastic Contact

Solid and elastic contact problems have been thoroughly investigated before. The most recent efforts incorporate the use of the Lennard-Jones (LJ) potential to describe the inter-surface forces that are present and substantial in micro-sized contact problems. But little work has been done on viscoelastic contact problems. Hence, there is a need to investigate the behaviour of a viscoelastic contact under the LJ interaction. This paper aims to investigate the deformation of an axisymmetric viscoelastic tip that is either pushed onto or pulled from a flat rigid surface. From existing elastic models, a mathematical model was developed to describe the contact problem in a viscoelastic context. This newly developed was solved via numerical means. The result is a model that readily accepts measureable physical properties and gives out the deformation of a viscoelastic tip.

A Molecular Model of Asperity Contact and Comparison to Continuum Based Models

2008 ◽  
Author(s):  
Wei Huang ◽  
Robert L. Jackson
Keyword(s):  
Contact Mechanics ◽  
Continuum Mechanics ◽  
Material Properties ◽  
Molecular Model ◽  
Small Scale ◽  
Elastic Contact ◽  
Asperity Contact ◽  
Molecular Forces ◽  
The Continuum

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 model is also compared to existing continuum mechanics based models developed originally by Hertz for elastic contact and later expanded by others to include plasticity. It appears that the predictions can be related to each other and that the continuum material properties can be related to the properties describing the molecular forces.

Experimental Identification of Elastic, Damping and Adhesion Forces in Collision of Spherical Sliders With Stationary Magnetic Disks

2004 ◽  
Author(s):  
Kyosuke Ono ◽  
Satoshi Oohara
Keyword(s):  
Adhesion Force ◽  
Contact Theory ◽  
Force Model ◽  
Adhesion Forces ◽  
Lubricant Thickness ◽  
Damping Force ◽  
Magnetic Disks ◽  
Magnetic Disk ◽  
Damping Effect ◽  
Experimental Identification

This paper deals with the experimental identification of elastic, damping and adhesion forces in the dynamic collision of a spherical slider with a stationary magnetic disk. We used rough Al2O3TiC and smooth glass spherical sliders with a radius of 1 mm, and magnetic disks with four different lubricant film thicknesses of 0, 1, 2, and 3 nm. We found that the Al2O3TiC slider shows ordinary approach and rebound processes, whereas the glass slider showed a velocity drop at the end of the rebound process when the lubricant thickness was 1, 2 and 3 nm. We identified the elastic force factors in the approaching and rebound processes, based on the Herztian contact theory, and the damping force factors based on a damping force model that is proportional to slider velocity and penetration depth (contact area). From the drop in velocity when the slider and disk separated, we found that the dynamic adhesion force is almost equal to the static pull-off force, except for with a 3nm lubricant thickness. The dynamic adhesion force with 3 nm lubricant thickness is significantly higher probably because of squeeze damping effect.

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