Local contact stress measurements at a rough interface

TL;DR

This paper introduces a MEMS-based sensor to measure detailed stress fields at rough elastomeric interfaces, enabling comparison with theoretical models and revealing effects of lubrication and compliance.

Contribution

It presents a novel MEMS device for spatially resolved stress measurement at rough interfaces and compares experimental data with FEM simulations under different conditions.

Findings

Measured stress profiles match FEM for smooth contacts.

Lubrication alters stress distribution profiles.

Load-dependent deviations from classical friction laws are observed.

Abstract

An original MEMS-based force sensing device is designed which allows to measure spatially resolved normal and tangential stress fields at the base of an elastomeric film. This device is used for the study of the contact stress between a rough film and a smooth glass sphere under normal load. The measured profiles are compared to Finite Elements Method calculations for a smooth contact with boundary conditions obeying Amontons-Coulomb's friction law. The accuracy of the measurements allows to discriminate between dry and lubricated contact conditions and to evidence load-dependent deviations from Amontons-Coulomb's profiles. These deviations are qualitatively interpreted by taking into account the finite compliance of the micro-contact population.