Source-linked AI summary
Experimental evidence of non-Amontons behaviour at a multicontact interface
Julien Scheibert, Alexis Prevost, Joel Frelat, Patrice Rey, Georges Debrégeas
TL;DR
The paper tests whether local Amontons-law FEM calculations capture normal stress fields in a multicontact interface. MEMS measurements show dry-contact deviations that diminish with load, while glycerol-lubricated profiles match frictionless calculations; the authors attribute the dry-contact deviation primarily to tangential interface compliance.
Problem
It is unclear how well smooth-surface FEM calculations using local rigid-plastic Amontons friction capture stress fields in a real multicontact interface.
Source: p. 1Method
The authors measure normal stress with a MEMS sensor beneath a rough PDMS film pressed against a glass sphere and compare profiles with FEM calculations using Amontons-law boundary conditions.
Source: pp. 1–2Results
Dry-contact profiles require a load-dependent effective friction coefficient below the macroscopic value, whereas glycerol-lubricated profiles are correctly captured by frictionless FEM.
Source: p. 4Takeaways & Limitations
The authors conclude that tangential compliance of the multicontact interface is primarily responsible for dry-contact deviations from local Amontons law.
Source: p. 5The MEMS also measures tangential stress, but its accuracy is insufficient for this study.
Source: p. 2
Abstract
from arXiv · showhide
We report on normal stress field measurements at the multicontact interface between a rough elastomeric film and a smooth glass sphere under normal load, using an original MEMS-based stress sensing device. These measurements are compared to Finite Elements Method calculations with boundary conditions obeying locally Amontons' rigid-plastic-like friction law with a uniform friction coefficient. In dry contact conditions, significant deviations are observed which decrease with increasing load. In lubricated conditions, the measured profile recovers almost perfectly the predicted profile. These results are interpreted as a consequence of the finite compliance of the multicontact interface, a mechanism which is not taken into account in Amontons' law.