Beyond quality and quantity: Spatial distribution of contact encodes frictional strength

Sam Dillavou, Yohai Bar-Sinai, Michael P. Brenner, Shmuel M. Rubinstein

Research output: Contribution to journalArticlepeer-review


Classically, the quantity of contact area AR between two bodies is considered a proxy for the force of friction. However, bond density across the interface - quality of contact - is also relevant, and contemporary debate often centers around the relative importance of these two factors. In this work, we demonstrate that a third factor, often overlooked, plays a significant role in static frictional strength: The spatial distribution of contact. We perform static friction measurements, μ, on three pairs of solid blocks while imaging the contact plane. By using linear regression on hundreds of image-μ pairs, we are able to predict future friction measurements with three to seven times better accuracy than existing benchmarks, including total quantity of contact area. Our model has no access to quality of contact, and we therefore conclude that a large portion of the interfacial state is encoded in the spatial distribution of contact, rather than its quality or quantity.

Original languageEnglish
Article numberL033001
JournalPhysical Review E
Issue number3
StatePublished - Sep 2022


FundersFunder number
Smith Family Fellowship
National Science Foundation
Office of Naval ResearchN00014-17-1-3029
Division of Mathematical SciencesDMS-1715477
Simons Foundation
Materials Research Science and Engineering Center, Harvard UniversityDMR-1420570


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