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Contact between rough surfaces and a criterion for macroscopic adhesion

Pastewka, Lars; Robbins, Mark O.

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 ne ... mehr

Zugehörige Institution(en) am KIT Institut für Angewandte Materialien - Computational Materials Science (IAM-CMS)
Publikationstyp Zeitschriftenaufsatz
Jahr 2014
Sprache Englisch
Identifikator DOI: 10.1073/pnas.1320846111
ISSN: 0027-8424
KITopen ID: 1000053787
Erschienen in Proceedings of the National Academy of Sciences of the United States of America
Band 111
Heft 9
Seiten 3298-3303
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