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Roughness

Dr. Hanaor - Department of Ceramic Materials - TU Berlin's picture

Electrical resistance at rough surfaces in contact

Electrical Contact Resistance of Fractal Rough Surfaces 

 

The presence of roughness at electrical contacts tends to involve contacting asperities across multiple scales. Depending on the nature of the contact between asperities on opposing surfaces, different conduction mechanisms take place. This is shown in the figure here.

Dr. Hanaor - Department of Ceramic Materials - TU Berlin's picture

Contact stiffness of rough surfaces

Contact stiffness of multiscale surfaces by truncation analysis

 

In this concise piece of work, an effective method is shown to gain new understandings into the role of surface structure in the field of contact mechanics. In particular, normal contact stiffness is correlated to parameters of surfaces' fractal dimension and amplitude. 

Mike Ciavarella's picture

are fractal surfaces adhesive? a new attempt on JMPS

In 2007 I wrote a question in Imechanica, IS THERE NO PULL-OFF FOR ADHESIVE FRACTAL SURFACES?

Clearly, in 2007 this question was too hard to answer.  I pointed there that Fuller and Tabor 1975 asperity theory predicted a weird limit for a true fractal surface, that of no stickiness for any fractal dimension or amplitude, in the limit.

marco.paggi's picture

Wiki surface - an open access encyclopedia of surfaces

Dear Mechanicians,

a new project at the IMT School for Advanced Studies Lucca (Lucca, Italy) has just been launched to create the first open access database of rough surfaces from nature and technology, see: 

http://musam.imtlucca.it/wikisurf.html

People are invited to contribute to the database by providing images of surfaces acquired using experimental techniques, as well as the corresponding elevation data field (raw x,y,z data in columns).

marco.paggi's picture

EUROMECH Colloquium 575 on Contact Mechanics and Coupled Problems in Surface Phenomena

Dear Colleague,
  we would like to inform you that the EUROMECH Colloquium 575 on “Contact Mechanics and Coupled Problems in Surface Phenomena” will take place in the IMT Institute for Advanced Studies Lucca (Lucca, Italy) from March 30, 2015 to April 2, 2015.  

Pradeep Sharma's picture

Surface Energy, Elasticity and the Homogenization of Rough Surfaces

The attached paper was recently accepted for publication in Journal of the Mechanics and Physics of Solids.

Wavelengths of surface features

I am working on the surface features of steel . I understand that surface features are broken down into various wavelengths and represented as Wa to We (0.1mm to 30mm wavelengths). Could some guide me to a reference which shows how to go about this process from the raw surface profile data ? Possibly, it involves Fourier Transforms, but I need a basic reference which shows how it is done .

 

Thanks!

 

Henry Tan's picture

Surface roughness evolution

With a shallow chemical etching the roughness with spatial frequency below a critical value grows while the roughness of higher frequency decays.

node/1312

Surface Roughness and Electrical Contact Resistance

J.R.Barber The contact of rough surfaces Surfaces are rough on the microscopic scale, so contact is restricted to a few `actual contact areas'. If a current flows between two contacting bodies, it has to pass through these areas, causing an electrical contact resistance. The problem can be seen as analogous to a large number of people trying to get out of a hall through a small number of doors.

Classical treatments of the problem are mostly based on the approximation of the surfaces as a set of `asperities' of idealized shape. The real surfaces are represented as a statistical distribution of such asperities with height above some datum surface. However, modern measurement techniques have shown surfaces have multiscale, quasi-fractal characteristics over a wide range of length scales. This makes it difficult to decide on what scale to define the asperities.

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