Dislocation drag and its influence on elastic precursor decay

TL;DR

This paper investigates how dislocation drag influences elastic precursor decay during high-stress shock impacts, emphasizing the importance of accurate modeling of dislocation behavior and density evolution in materials.

Contribution

It introduces a first-principles based model for dislocation drag considering stress and dislocation character, and explores dislocation density evolution in anisotropic fcc metals.

Findings

Dislocation drag significantly affects elastic precursor decay.

Modeling dislocation density evolution remains highly uncertain.

Dislocation character influences drag and deformation behavior.

Abstract

Plastic deformation is mediated by the creation and movement of dislocations, and at high stress the latter is dominated by dislocation drag from phonon wind. By simulating a 1-D shock impact problem we analyze the importance of accurately modeling dislocation drag and dislocation density evolution in the high stress regime. Dislocation drag is modeled according to a first-principles derivation as a function of stress and dislocation character, and its temperature and density dependence are approximated to the extent currently known. Much less is known about dislocation density evolution, leading to far greater uncertainty in these model parameters. In studying anisotropic fcc metals with character dependent dislocations, the present work generalizes similar earlier studies by other authors.