Rough contact mechanics for graded bulk rheology: The role of small-scale wavelengths on rubber friction

TL;DR

This paper introduces a numerical model to predict the contact mechanics of graded viscoelastic rubber surfaces in steady sliding, highlighting how small-scale roughness influences friction and contact area.

Contribution

It develops a Fourier-based model for graded rheology and analyzes the impact of small-scale wavelengths on rubber friction and contact mechanics.

Findings

Contact mechanics converge to asymptotes with increased small-scale roughness.

Effective interface properties depend on the small-scale roughness content.

Rheology of the confinement significantly affects contact behavior.

Abstract

We present a numerical model for the prediction of the rough contact mechanics of a viscoelastic block, with graded rheology, in steady sliding contact with a randomly rough rigid surface. In particular, we derive the effective surface response of a stepwise or continuously-graded block in the Fourier domain, which is then embedded in a Fourier-based residuals molecular dynamic formulation of the contact mechanics. Finally we discuss on the role of small-scale wavelengths on rubber friction and contact area, and we demonstrate that the rough contact mechanics exhibits effective interface properties which converge to asymptotes upon increase of the small-scale roughness content, when a realistic rheology of the confinement is taken into account.