Contact between rough surfaces and a criterion for macroscopic adhesion
At the molecular scale, there are strong attractive interactions between surfaces, yet few macroscopic surfaces are sticky. Extensive simulations of contact by adhesive surfaces with roughness on nanometer to micrometer scales are used to determine how roughness reduces the area where atoms contact...
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Published in | Proceedings of the National Academy of Sciences - PNAS Vol. 111; no. 9; pp. 3298 - 3303 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
United States
National Academy of Sciences
04.03.2014
National Acad Sciences |
Subjects | |
Online Access | Get full text |
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Summary: | At the molecular scale, there are strong attractive interactions between surfaces, yet few macroscopic surfaces are sticky. Extensive simulations of contact by adhesive surfaces with roughness on nanometer to micrometer scales are used to determine how roughness reduces the area where atoms contact and thus weakens adhesion. The material properties, adhesive strength, and roughness parameters are varied by orders of magnitude. In all cases, the area of atomic contact is initially proportional to the load. The prefactor rises linearly with adhesive strength for weak attractions. Above a threshold adhesive strength, the prefactor changes sign, the surfaces become sticky, and a finite force is required to separate them. A parameter-free analytic theory is presented that describes changes in these numerical results over up to five orders of magnitude in load. It relates the threshold adhesive strength to roughness and material properties, explaining why most macroscopic surfaces do not stick. The numerical results are qualitatively and quantitatively inconsistent with classical theories based on the Greenwood−Williamson approach that neglect the range of adhesion and do not include asperity interactions. |
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Bibliography: | http://dx.doi.org/10.1073/pnas.1320846111 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Author contributions: L.P. and M.O.R. designed research; L.P. and M.O.R. performed research; L.P. and M.O.R. analyzed data; L.P. and M.O.R. wrote the paper; and L.P. wrote the contact mechanics code and carried out simulations. Edited* by Jacob N. Israelachvili, University of California, Santa Barbara, CA, and approved January 23, 2014 (received for review November 5, 2013) |
ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.1320846111 |