Plastic deformation of tubular crystals by dislocation glide

TL;DR

This paper investigates how dislocation glide causes plastic deformation in tubular crystals with variable radii, revealing mechanisms for lattice reconfiguration influenced by tube geometry and bending rigidity through theory and simulation.

Contribution

It introduces a new understanding of dislocation-mediated plasticity in tubular crystals with variable radii, extending previous work on fixed-radius systems.

Findings

Dislocation glide enables low-energy lattice reconfiguration.

Tube radius and helicity significantly influence dislocation mechanics.

Strong bending rigidity can arrest deformation processes.

Abstract

Tubular crystals, two-dimensional lattices wrapped into cylindrical topologies, arise in many contexts, including botany and biofilaments, and in physical systems such as carbon nanotubes. The geometrical principles of botanical phyllotaxis, describing the spiral packings on cylinders commonly found in nature, have found application in all these systems. Several recent studies have examined defects in tubular crystals associated with crystalline packings that must accommodate a fixed tube radius. Here, we study the mechanics of tubular crystals with variable tube radius, with dislocations interposed between regions of different phyllotactic packings. Unbinding and separation of dislocation pairs with equal and opposite Burgers vectors allow the growth of one phyllotactic domain at the expense of another. In particular, glide separation of dislocations offers a low-energy mode for plastic deformations of solid tubes in response to external stresses, reconfiguring the lattice step by step. Through theory and simulation, we examine how the tube's radius and helicity affects, and is in turn altered by, the mechanics of dislocation glide. We also discuss how a sufficiently strong bending rigidity can alter or arrest the deformations of tubes with small radii.