scholarly journals The gauge theory of dislocations: A nonuniformly moving screw dislocation

2010 ◽  
Vol 374 (30) ◽  
pp. 3092-3098 ◽  
Author(s):  
Markus Lazar
Keyword(s):  
Gauge Theory ◽  
Screw Dislocation ◽  
Nonuniformly Moving

scholarly journals The gauge theory of dislocations: a uniformly moving screw dislocation

2009 ◽  
Vol 465 (2108) ◽  
pp. 2505-2520 ◽  
Author(s):  
Markus Lazar
Keyword(s):  
Gauge Theory ◽  
Gauge Field ◽  
Screw Dislocation ◽  
Equations Of Motion ◽  
Dislocation Core ◽  
Point Of View ◽  
Theoretical Point ◽  
Theoretical Formulation ◽  
Screw Dislocations ◽  
Mach Cones

In this paper, we present the equations of motion of a moving screw dislocation in the framework of the translation gauge theory of dislocations. In the gauge field theoretical formulation, a dislocation is a massive gauge field. We calculate the gauge field theoretical solutions of a uniformly moving screw dislocation. We give the subsonic and supersonic solutions. Thus, supersonic dislocations are not forbidden from the field theoretical point of view. We show that the elastic divergences at the dislocation core are removed. We also discuss the Mach cones produced by supersonic screw dislocations.

Gauge-field-theory solution of the elastic state of a screw dislocation in a dispersive (non-local) crystalline solid

2005 ◽  
Vol 461 (2056) ◽  
pp. 1081-1095 ◽  
Author(s):  
P Sharma ◽  
S Ganti
Keyword(s):  
Field Theory ◽  
Gauge Theory ◽  
Gauge Field ◽  
Screw Dislocation ◽  
Gauge Length ◽  
Effective Length ◽  
Gauge Field Theory ◽  
Length Scale ◽  
Present Solution ◽  
Non Local

The relaxed state of a type of topological defect (screw dislocation) located in a dispersive (non-local) elastic solid is discussed from a viewpoint of gauge field theory. The starting point of this work is the non-local elastic Lagrangian, that is, like its classic elastic counterpart, globally gauge invariant under the Euclidean group of transformations O (3)▹ (3). When compared with gauge solutions of the same problem predicated on the classical elastic Lagrangian, the present solution sheds some interesting insights into the nature of non-locality-gauge field interactions. Both the (3) gauge theory of dislocations (predicated on breaking of the translational symmetry) and the phenomenological non-local elasticity introduce their own respective characteristic length-scale parameters in the elastic equilibrium of dislocations while removing unphysical singularities. In the present work we show that, surprisingly, attempts to elucidate gauge interactions in a dispersive or non-local medium lead to functionally the same solution as in the gauge theory based on local elasticity, albeit, the gauge length-scale must be replaced by an effective length-scale measure. In particular, the non-local and the gauge length-scale combine in a nonlinear fashion to yield the aforementioned effective length-scale. Our results allow one to immediately write the solution of most screw dislocation problems in the gauge non-local theory of defects, provided the counterpart gauge solution based on classical elasticity is known.

A New Defect in Polyethylene Single Crystals

1973 ◽  
Vol 31 ◽  
pp. 70-71
Author(s):  
E. L. Thomas ◽  
S. L. Sass
Keyword(s):  
Single Crystals ◽  
Screw Dislocation ◽  
Small Distance ◽  
Dipole Model ◽  
Dislocation Dipole ◽  
Chain Folding ◽  
Black And White ◽  
Polymer Crystal ◽  
Different Types

In polyethylene single crystals pairs of black and white lines spaced 700-3,000Å apart, parallel to the [100] and [010] directions, have been identified as microsector boundaries. A microsector is formed when the plane of chain folding changes over a small distance within a polymer crystal. In order for the different types of folds to accommodate at the boundary between the 2 fold domains, a staggering along the chain direction and a rotation of the chains in the plane of the boundary occurs. The black-white contrast from a microsector boundary can be explained in terms of these chain rotations. We demonstrate that microsectors can terminate within the crystal and interpret the observed terminal strain contrast in terms of a screw dislocation dipole model.

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