Giant Wave-Drag Enhancement of Friction in Sliding Carbon Nanotubes

TL;DR

This paper demonstrates that resonant excitation of phonons in sliding carbon nanotubes causes a significant increase in friction, akin to wave drag near the speed of sound, with implications for nanoscale mechanical systems.

Contribution

It reveals a novel wave-drag-like friction enhancement mechanism in sliding nanotubes due to phonon resonance, expanding understanding of nanoscale friction phenomena.

Findings

Friction dramatically increases when phonons with group velocity near sliding velocity are excited.

The effect varies with atomic structure and can occur in multiple velocity ranges.

The phenomenon is likely applicable to other nanoscale mechanical systems.

Abstract

Molecular dynamics simulations of coaxial carbon nanotubes in relative sliding motion reveal a striking enhancement of friction when phonons whose group velocity is close to the sliding velocity of the nanotubes are resonantly excited. The effect is analogous to the dramatic increase in air drag experienced by aircraft flying close to the speed of sound, but differs in that it can occur in multiple velocity ranges with varying magnitude, depending on the atomic level structures of the nanotubes. The phenomenon is a general one that may occur in other nanoscale mechanical systems.