Modeling dislocation density evolution in continuum crystal plasticity

Dislocations are the singly most important material defects in crystal plasticity, and although dislocation mechanics has long been understood as the underlying physical basis for continuum crystal plasticity formulations, explicit consideration of crystallo- graphic dislocation mechanics has been largely absent in working constitutive models. In light of recent theoretical developments in dislocation dynamics, and the introduc- tion of geometrically necessary dislocation (GND) density in continuum formulations through plastic strain gradients, a single crystal plasticity model based on dislocation density state variables is developed. The density state variables evolve from initial conditions according to equations based on fundamental concepts in dislocation me- chanics such as the conservation of Burgers vector in multiplication and annihilation processes. Along with those processes that account for bulk statistical dislocation evolution, the evolving polarity due to dislocation species flux divergences may be in- cluded to detail the length-scale dependence of mechanical properties on the micron level. The full dislocation density description of plasticity allows a simple evaluation of the role of GND density in non-homogeneously deforming bodies. A local version of the constitutive model, which captures the bulk processes of dislocation multiplication and annihilation during plastic deformation, is implemented within a finite element framework to investigate the poly-slip behavior of aluminum single crystals under tension.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2001

Author dc:creator

• Arsenlis, Athanasios, 1975-

Advisor dc:contributor.advisor

• David M. Parks.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/36679

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/36679