Velocity weakening and possibility of aftershocks in nanofriction experiments

TL;DR

This paper investigates how certain mechanisms in nanofriction experiments can cause velocity weakening and aftershocks, drawing parallels to seismic phenomena at the microscale using generalized Prandtl-Tomlinson models.

Contribution

It introduces models showing how viscous relaxation and aging effects can lead to velocity weakening and aftershocks in nanoscale friction, akin to macroscale seismic behavior.

Findings

Velocity weakening can arise from viscous relaxation and aging effects.

Aftershocks occur at low sliding velocities in the models.

Microscale friction exhibits features similar to seismic aftershocks.

Abstract

We study the frictional behavior of small contacts as those realized in the atomic force microscope and other experimental setups, in the framework of generalized Prandtl-Tomlinson models. Particular attention is paid to mechanisms that generate velocity weakening, namely a decreasing average friction force with the relative sliding velocity.The mechanisms studied model the possibility of viscous relaxation, or aging effects in the contact. It is found that, in addition to producing velocity weakening, these mechanisms can also produce aftershocks at sufficiently low sliding velocities. This provides a remarkable analogy at the microscale, of friction properties at the macroscale, where aftershocks and velocity weakening are two fundamental features of seismic phenomena.