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On the Proportionality Between Area and Load in Line Contacts
The relative contact area of rough surface contacts is known to increase linearly with reduced pressure, with proportionality factor [Formula: see text] . In its common definition, the reduced pressure contains the root-mean-square gradient (RMSG) of the surface. Although easy to measure, the RMSG o...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Springer US
2018
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6417384/ https://www.ncbi.nlm.nih.gov/pubmed/30956514 http://dx.doi.org/10.1007/s11249-018-1061-7 |
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author | van Dokkum, J. S. Khajeh Salehani, M. Irani, N. Nicola, L. |
author_facet | van Dokkum, J. S. Khajeh Salehani, M. Irani, N. Nicola, L. |
author_sort | van Dokkum, J. S. |
collection | PubMed |
description | The relative contact area of rough surface contacts is known to increase linearly with reduced pressure, with proportionality factor [Formula: see text] . In its common definition, the reduced pressure contains the root-mean-square gradient (RMSG) of the surface. Although easy to measure, the RMSG of the entire surface does not coincide, at small loads, with the RMSG over the actual contact area [Formula: see text] , which gives a better description of the contact between rough surfaces. It was recently shown that, for Hertzian contacts, linearity between area and load is indeed obtained only if the RMSG is determined over the actual contact area. Similar to surface contacts, in line contacts, numerical data are often studied using theories that predict linearity by design. In this work, we revisit line contact problems and examine whether or not the assumption of linearity for line contacts holds true. We demonstrate, using Green’s function molecular dynamics simulations, that [Formula: see text] for line contacts is not a constant: It depends on both the reduced pressure and the Hurst exponent. However, linearity holds when the RMSG is measured over the actual contact area. In that case, we could compare [Formula: see text] for line and surface contacts and found that their ratio is approximately 0.9. Finally, by analytically deriving the proportionality factor using [Formula: see text] in the original model of Greenwood and Williamson, a value is obtained that is surprisingly in good agreement with our numerical results for rough surface contacts. |
format | Online Article Text |
id | pubmed-6417384 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | Springer US |
record_format | MEDLINE/PubMed |
spelling | pubmed-64173842019-04-03 On the Proportionality Between Area and Load in Line Contacts van Dokkum, J. S. Khajeh Salehani, M. Irani, N. Nicola, L. Tribol Lett Original Paper The relative contact area of rough surface contacts is known to increase linearly with reduced pressure, with proportionality factor [Formula: see text] . In its common definition, the reduced pressure contains the root-mean-square gradient (RMSG) of the surface. Although easy to measure, the RMSG of the entire surface does not coincide, at small loads, with the RMSG over the actual contact area [Formula: see text] , which gives a better description of the contact between rough surfaces. It was recently shown that, for Hertzian contacts, linearity between area and load is indeed obtained only if the RMSG is determined over the actual contact area. Similar to surface contacts, in line contacts, numerical data are often studied using theories that predict linearity by design. In this work, we revisit line contact problems and examine whether or not the assumption of linearity for line contacts holds true. We demonstrate, using Green’s function molecular dynamics simulations, that [Formula: see text] for line contacts is not a constant: It depends on both the reduced pressure and the Hurst exponent. However, linearity holds when the RMSG is measured over the actual contact area. In that case, we could compare [Formula: see text] for line and surface contacts and found that their ratio is approximately 0.9. Finally, by analytically deriving the proportionality factor using [Formula: see text] in the original model of Greenwood and Williamson, a value is obtained that is surprisingly in good agreement with our numerical results for rough surface contacts. Springer US 2018-08-02 2018 /pmc/articles/PMC6417384/ /pubmed/30956514 http://dx.doi.org/10.1007/s11249-018-1061-7 Text en © The Author(s) 2018 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. |
spellingShingle | Original Paper van Dokkum, J. S. Khajeh Salehani, M. Irani, N. Nicola, L. On the Proportionality Between Area and Load in Line Contacts |
title | On the Proportionality Between Area and Load in Line Contacts |
title_full | On the Proportionality Between Area and Load in Line Contacts |
title_fullStr | On the Proportionality Between Area and Load in Line Contacts |
title_full_unstemmed | On the Proportionality Between Area and Load in Line Contacts |
title_short | On the Proportionality Between Area and Load in Line Contacts |
title_sort | on the proportionality between area and load in line contacts |
topic | Original Paper |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6417384/ https://www.ncbi.nlm.nih.gov/pubmed/30956514 http://dx.doi.org/10.1007/s11249-018-1061-7 |
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