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Chemical aging of large-scale randomly rough frictional contacts

: Li, Z.; Pastewka, L.; Szlufarska, I.


Physical Review. E 98 (2018), No.2, Art.023001
ISSN: 1063-651X
ISSN: 1539-3755
ISSN: 2470-0045
ISSN: 2470-0053
ISSN: 1550-2376
Deutsche Forschungsgemeinschaft DFG
PA 2023/2
Journal Article
Fraunhofer IWM ()

It has been shown that contact aging due to chemical reactions in single asperity contacts can have a significant effect on friction. However, it is currently unknown how chemically induced contact aging of friction depends on roughness that is typically encountered in macroscopic rough contacts. Here we develop an approach that brings together a kinetic Monte Carlo model of chemical aging with a contact mechanics model of rough surfaces based on the boundary element method to determine the magnitude of chemical aging in silica-silica contacts with random roughness. Our multiscale model predicts that chemical aging for randomly rough contacts has a logarithmic dependence on time. It also shows that friction aging switches from a linear to a nonlinear dependence on the applied load as the load increase. We discover that surface roughness affects the aging behavior primarily by modifying the real contact area and the local contact pressure, whereas the effect of contact morphology is relatively small. Our results demonstrate how understanding of chemical aging can be translated from studies of single asperity contacts to macroscopic rough contacts.