On the viscous dissipation caused by randomly rough indenters in smooth sliding motion

TL;DR

This paper investigates viscous dissipation caused by randomly rough indenters in smooth sliding motion, using Green's function molecular dynamics, revealing velocity-dependent damping and comparing results with Persson's theory.

Contribution

It applies Green's function molecular dynamics to study viscous dissipation in rough contact sliding, validating and comparing with Persson's theory across different models.

Findings

Damping linear in velocity at small v

Maximum damping at intermediate v

Quantitative agreement with Persson's theory up to intermediate velocities

Abstract

The viscous dissipation between rigid, randomly rough indenters and linearly elastic counter bodies sliding past them is investigated using Green's function molecular dynamics. The study encompasses a variety of models differing in the height spectra properties of the rigid indenter, in the viscoelasticity of the elastomer, and in their interaction. All systems reveal the expected damping linear in sliding velocity $v$ at small $v$ and a pronounced maximum at intermediate $v$. Persson's theory of rubber friction, which is adopted to the studied model systems, reflects all observed trends. However, close quantitative agreement is only found up to intermediate sliding velocities. Relative errors in the friction force become significant once the contact area is substantially reduced by sliding.