scholarly journals Effective mobility of BCC dislocations in two-dimensional discrete dislocation plasticity

2021 ◽  
Vol 187 ◽  
pp. 110129
Author(s):  
T. Katiyar ◽  
E. Van der Giessen
Keyword(s):  
Two Dimensional ◽  
Discrete Dislocation ◽  
Dislocation Plasticity ◽  
Effective Mobility

Discrete Dislocation Plasticity Approach to Fast Moving Dislocations

1999 ◽  
Vol 578 ◽  
Author(s):  
A. Roos ◽  
E. Metselaar ◽  
J.Th.M. De Hosson ◽  
E. van der Giessen
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Strain Rates ◽  
Two Dimensional ◽  
Relativistic Case ◽  
Discrete Dislocation ◽  
Dislocation Plasticity ◽  
Isotropic Elasticity ◽  
Very High

AbstractThis paper concentrates on application of the so-called Discrete Dislocation Plasticity to high strain rate deformations. In particular the question is addressed if the DDP approach may capture the specific processes taking place at high strain rates. In particular the paper reports on tests of the validity of some approximations and provides some sample runs to show the applicability of the method. In assessing the results, one has to keep in mind two underpinning aspects: (1) the model is two-dimensional and (2) the results hold only in the regime where linear isotropic elasticity is valid. It was concluded that accelerations can not be neglected at very high strain rate deformations, both for the conventional and the relativistic case.

scholarly journals A dynamic discrete dislocation plasticity method for the simulation of plastic relaxation under shock loading

2013 ◽  
Vol 469 (2156) ◽  
pp. 20130141 ◽  
Author(s):  
Beñat Gurrutxaga-Lerma ◽  
Daniel S. Balint ◽  
Daniele Dini ◽  
Daniel E. Eakins ◽  
Adrian P. Sutton
Keyword(s):  
Shock Loading ◽  
Time Dependent ◽  
Plastic Relaxation ◽  
Uniform Motion ◽  
Infinite Plane ◽  
Two Dimensional ◽  
Elastic Fields ◽  
Discrete Dislocation ◽  
Dislocation Plasticity ◽  
Discrete Dislocations

In this article, it is demonstrated that current methods of modelling plasticity as the collective motion of discrete dislocations, such as two-dimensional discrete dislocation plasticity (DDP), are unsuitable for the simulation of very high strain rate processes (10 6  s −1 or more) such as plastic relaxation during shock loading. Current DDP models treat dislocations quasi-statically, ignoring the time-dependent nature of the elastic fields of dislocations. It is shown that this assumption introduces unphysical artefacts into the system when simulating plasticity resulting from shock loading. This deficiency can be overcome only by formulating a fully time-dependent elastodynamic description of the elastic fields of discrete dislocations. Building on the work of Markenscoff & Clifton, the fundamental time-dependent solutions for the injection and non-uniform motion of straight edge dislocations are presented. The numerical implementation of these solutions for a single moving dislocation and for two annihilating dislocations in an infinite plane are presented. The application of these solutions in a two-dimensional model of time-dependent plasticity during shock loading is outlined here and will be presented in detail elsewhere.

scholarly journals Discrete Dislocation Plasticity

2005 ◽  
pp. 1115-1131 ◽  
Author(s):  
E. Van der Giessen ◽  
A. Needleman
Keyword(s):  
Discrete Dislocation ◽  
Dislocation Plasticity

A Discrete Dislocation Plasticity Analysis of Plane-Strain Indentation of a Single-Crystal Half-Space by a Smooth and a Rough Rigid Asperity

2010 ◽  
Author(s):  
X. Yin ◽  
K. Komvopoulos
Keyword(s):  
Single Crystal ◽  
Plane Strain ◽  
Half Space ◽  
Crystal Surface ◽  
Normal Load ◽  
Surface Profile ◽  
Dislocation Source ◽  
Discrete Dislocation ◽  
Dislocation Plasticity ◽  
Edge Dislocations

A discrete dislocation plasticity analysis of plane-strain indentation of a single-crystal half-space by a smooth or rough (fractal) rigid asperity is presented. The emission, movement, and annihilation of edge dislocations are incorporated in the analysis through a set of constitutive rules [1,2]. It is shown that the initiation of the first dislocation is controlled by the subsurface Hertzian stress field and occurs in the ±45° direction with respect to the normal of the crystal surface, in agreement with the macroscopic yielding behavior of the indented halfspace. For fixed slip-plane direction, the dislocation density increases with the applied normal load and dislocation source density. The dislocation multiplication behavior at a given load is compared with that generated by a rough indenter with a fractal surface profile. The results of the analysis provide insight into yielding and plastic deformation phenomena in indented single-crystal materials.

scholarly journals Discrete dislocation plasticity and crack tip fields in single crystals

2001 ◽  
Vol 49 (9) ◽  
pp. 2133-2153 ◽  
Author(s):  
E. Van der Giessen ◽  
V.S. Deshpande ◽  
H.H.M. Cleveringa ◽  
A. Needleman
Keyword(s):  
Single Crystals ◽  
Crack Tip ◽  
Crack Tip Fields ◽  
Discrete Dislocation ◽  
Dislocation Plasticity

scholarly journals Discrete dislocation plasticity analysis of single slip tension

2005 ◽  
Vol 400-401 ◽  
pp. 154-157 ◽  
Author(s):  
V.S. Deshpande ◽  
A. Needleman ◽  
E. Van der Giessen
Keyword(s):  
Single Slip ◽  
Discrete Dislocation ◽  
Dislocation Plasticity

Climb-Enabled Discrete Dislocation Plasticity Analysis of the Deformation of a Particle Reinforced Composite

2015 ◽  
Vol 82 (7) ◽  
Author(s):  
C. Ayas ◽  
L. C. P. Dautzenberg ◽  
M. G. D. Geers ◽  
V. S. Deshpande
Keyword(s):  
Particle Size ◽  
Size Effect ◽  
Strain Hardening ◽  
Volume Fraction ◽  
Dislocation Motion ◽  
Dislocation Climb ◽  
Discrete Dislocation ◽  
Dislocation Plasticity ◽  
Wall Structures ◽  
The Matrix

The shear deformation of a composite comprising elastic particles in a single crystal elastic–plastic matrix is analyzed using a discrete dislocation plasticity (DDP) framework wherein dislocation motion occurs via climb-assisted glide. The topology of the reinforcement is such that dislocations cannot continuously transverse the matrix by glide-only without encountering the particles that are impenetrable to dislocations. When dislocation motion is via glide-only, the shear stress versus strain response is strongly strain hardening with the hardening rate increasing with decreasing particle size for a fixed volume fraction of particles. This is due to the formation of dislocation pile-ups at the particle/matrix interfaces. The back stresses associated with these pile-ups result in a size effect and a strong Bauschinger effect. By contrast, when dislocation climb is permitted, the dislocation pile-ups break up by forming lower energy dislocation wall structures at the particle/matrix interfaces. This results in a significantly reduced size effect and reduced strain hardening. In fact, with increasing climb mobility an “inverse size” effect is also predicted where the strength decreases with decreasing particle size. Mass transport along the matrix/particle interface by dislocation climb causes this change in the response and also results in a reduction in the lattice rotations and density of geometrically necessary dislocations (GNDs) compared to the case where dislocation motion is by glide-only.

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