Simple Law for Third-Body Friction

Fei Deng, Georgios Tsekenis, Shmuel M. Rubinstein*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


A key difficulty to understanding friction is that many physical mechanisms contribute simultaneously. Here we investigate third-body frictional dynamics in a model experimental system that eliminates first-body interaction, wear, and fracture, and concentrates on the elastic interaction between sliding blocks and third bodies. We simultaneously visualize the particle motion and measure the global shear force. By systematically increasing the number of foreign particles, we find that the frictional dissipation depends only on the size ratio between surface asperities and the loose particles, irrespective of the particle's size or the surface's roughness. When the particles are comparable in size to the surface features, friction increases linearly with the number of particles. For particles smaller than the surface features, friction grows sublinearly with the number of particles. Our findings suggest that matching the size of surface features to the size of potential contaminants may be a good strategy for reliable lubrication.

Original languageAmerican English
Article number135503
JournalPhysical Review Letters
Issue number13
StatePublished - 5 Apr 2019
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2019 American Physical Society.


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