The Effect of Multipoles on the Elasto-Plastic Properties of a Crystal: Theory and 3D Dislocation Dynamics Modeling

2021 ◽  
pp. 1-22
Author(s):  
Abu Bakar Siddique ◽  
Hojun Lim ◽  
Tariq Khraishi
Keyword(s):  
Plastic Deformation ◽  
Dislocation Dynamics ◽  
Dynamics Modeling ◽  
Proportional Limit ◽  
Softening Effect ◽  
Plastic Properties ◽  
Discrete Dislocation Dynamics ◽  
Scale Modeling ◽  
Discrete Dislocation ◽  
Elastoplastic Properties

Abstract Plastic deformation in metals is dominated by the interactions among dislocations and other defects inside the crystal. A large number of dislocation multipoles (dipoles, tripoles, quadrupoles, etc.) can form during plastic deformation. Depending on the relative position and the orientation of the dislocations, interactions in and between multipoles can change the elastoplastic properties of a material. The authors of this article investigate the effect of dislocation multipoles on the elastoplastic properties of a material. This is performed under different multipole configurations (i.e. the distance between active glide planes and the signs of the dislocations) using a 3D Discrete Dislocation Dynamics (DDD) code. The simulations show that multipoles exhibit a hardening/softening effect when the sign of the dislocations involved is the same, and a hardening effect only when the dislocations are of opposite sign to nearby ones. The distance between the two neighboring dislocations was also affecting the proportional limit for the material. Such hardening or flow stress results, as in this study, can be incorporated into larger-scale modeling work.

A discrete dislocation dynamics modeling for thermal fatigue of preferred oriented copper via patterns

2010 ◽  
Vol 63 (7) ◽  
pp. 788-791 ◽  
Author(s):  
Gyu Seok Kim ◽  
Marc C. Fivel ◽  
Hyo-Jong Lee ◽  
Chansun Shin ◽  
Heung Nam Han ◽  
...  
Keyword(s):  
Thermal Fatigue ◽  
Dislocation Dynamics ◽  
Dynamics Modeling ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation ◽  
Preferred Oriented

FFT based approaches in micromechanics: fundamentals, methods and applications

2021 ◽  
Author(s):  
Sergio Lucarini ◽  
Manas Vijay Upadhyay ◽  
Javier Segurado
Keyword(s):  
Dislocation Dynamics ◽  
Homogenization Problem ◽  
Multi Scale ◽  
Discrete Dislocation Dynamics ◽  
Scale Modeling ◽  
Damage And Fracture ◽  
Discrete Dislocation ◽  
Displacement Based ◽  
Selection Of ◽  
Computational Micromechanics

Abstract FFT methods have become a fundamental tool in computational micromechanics since they were first proposed in 1994 by H. Moulinec and P. Suquet for the homogenization of composites. From that moment on many dierent approaches have been proposed for a more accurate and efficient resolution of the non- linear homogenization problem. Furthermore, the method has been pushed beyond its original purpose and has been adapted to many other problems including continuum and discrete dislocation dynamics, multi-scale modeling or homogenization of coupled problems as fracture or multiphysical problems. In this paper, a comprehensive review of FFT approaches for micromechanical simulations will be made, covering the basic mathematical aspects and a complete description of a selection of approaches which includes the original basic scheme, polarization based methods, Krylov approaches, Fourier-Galerkin and displacement-based methods. The paper will present then the most relevant applications of the method in homogenization of composites, polycrystals or porous materials including the simulation of damage and fracture. It will also include an insight into synergies with experiments or its extension towards dislocation dynamics, multi-physics and multi-scale problems. Finally, the paper will analyze the current limitations of the method and try to analyze the future of the application of FFT approaches in micromechanics.

A study of the submicron indent-induced plastic deformation

1999 ◽  
Vol 14 (6) ◽  
pp. 2251-2258 ◽  
Author(s):  
C. F. Robertson ◽  
M. C. Fivel
Keyword(s):  
Plastic Deformation ◽  
Three Dimensional ◽  
Dislocation Nucleation ◽  
Dislocation Dynamics ◽  
Dynamics Simulation ◽  
Nanoindentation Test ◽  
Experimental Conditions ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation ◽  
Transmission Electron

A new method has been developed to achieve a better understanding of submicron indent-induced plastic deformation. This method combines numerical modeling and various experimental data and techniques. Three-dimensional discrete dislocation dynamics simulation and the finite element method (FEM) were used to model the experimental conditions associated with nanoindentation testing in fcc crystals. Transmission electron microscopy (TEM) observations of the indent-induced plastic volume and analysis of the experimental loading curve help in defining a complete set of dislocation nucleation rules, including the shape of the nucleated loops and the corresponding macroscopic loading. A validation of the model is performed through direct comparisons between a simulation and experiments for a nanoindentation test on a [001] copper single crystal up to 50 nm deep.

Statistical analysis and stochastic dislocation-based modeling of microplasticity

2015 ◽  
Vol 24 (3-4) ◽  
pp. 105-113 ◽  
Author(s):  
Olga Kapetanou ◽  
Vasileios Koutsos ◽  
Efstathios Theotokoglou ◽  
Daniel Weygand ◽  
Michael Zaiser
Keyword(s):  
Plastic Deformation ◽  
Complex Dynamics ◽  
Dislocation Dynamics ◽  
Small Samples ◽  
Plastic Behavior ◽  
Stochastic Description ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation ◽  
Plastic Deformation Behavior ◽  
Macroscopic Plasticity

AbstractPlastic deformation of micro- and nanoscale samples differs from macroscopic plasticity in two respects: (i) the flow stress of small samples depends on their size, and (ii) the scatter of plastic deformation behavior increases significantly. In this work, we focus on the scatter of plastic behavior. We statistically characterize the deformation process of micropillars using results from discrete dislocation dynamics (DDD) simulations. We then propose a stochastic microplasticity model that uses the extracted information to make statistical predictions regarding the micropillar stress-strain curves. This model aims to map the complex dynamics of interacting dislocations onto stochastic processes involving the continuum variables of stress and strain. Therefore, it combines a classical continuum description of the elastic-plastic problem with a stochastic description of plastic flow. We compare the model predictions with the underlying DDD simulations and outline potential future applications of the same modeling approach.

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