Numerical Simulation 0f Dislocation Patterns during Plastic Deformation

Ghoniem, Nasr M.; Amodeo, R. J.

doi:10.1007/978-94-009-0593-1_21

Cited by 15 publications

(7 citation statements)

References 40 publications

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“…This threshold is lower than the one obtained in earlier studies 716, 277, where the gliding velocity was considered as a constant, which rules out cross-diffusion terms in the linear evolution matrix ( K m = 0 ), and yields: SO* (26) If the dominant process for instability corresponds to the pinning of mobile dislocations by static dipoles or junctions (n = 2), one has: 1 + …”

Section: Stability Analysis and Bifurcationsmentioning

confidence: 70%

On Dislocation Patterning: Revisiting the W-A Model Part I: The Role of Gradient Terms in Dislocation Dynamics

Walgraef¹,

Aifantis²

2009

Journal of the Mechanical Behavior of Materials

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The Walgraef-Aifantis reaction-diffusion framework (W-A model) for dislocation patterning, proposed a quarter of a century ago, is revisited in view of new advances made in the field, including stochastic aspects.In the course of plastic deformation induced by dislocation glide, dislocation distributions, which are rather uniform at the beginning, quickly become unstable as deformation proceeds and undergo successive transitions towards various types of spatial patterns such as walls, cells, slip bands, labyrinth structures, etc.In the initial W-A model it was shown how the coupled nonlinear evolution of forest and gliding dislocation densities can generate spatially periodic dislocation patterns during cyclic deformation, commonly known as ladder structures of persistent slip bands. This model is updated here (Part I), to take care properly of the gradient terms of the mobile dislocation dynamics. It is shown that these terms generate space-dependent, nonlinear, self-and cross-diffusion terms, but also space-dependent advection terms which affect pattern formation and stability. Furthermore, it is argued that persistent slip bands nucleate preferentially through front propagation from stress inhomogeneities. The highly anisotropic character of the propagation velocity accounts for fast propagation in the slip direction, and very slow propagation in the climb direction. Next (Part II), the model is updated by incorporating the basics of the recently advanced stochastic/statistical approach of Groma-Zaiser and co-workers. It is shown that the resulting framework can conveniently describe self-assembly and self-organization phenomena as the external stress is increased. 49

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Section: Stability Analysis and Bifurcationsmentioning

confidence: 70%

On Dislocation Patterning: Revisiting the W-A Model Part I: The Role of Gradient Terms in Dislocation Dynamics

Walgraef¹,

Aifantis²

2009

Journal of the Mechanical Behavior of Materials

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“…Their dislocation-based creep model was initially developed to predict high-temperature deformation under arbitrary time-dependent stress and temperature histories for engineering materials. Their comprehensive dislocation creep model is based on earlier developments in creep theory [2]. The inclusion of sub-grain microstructure evolution is a key aspect of this model, as recognized earlier by Holt [3].…”

Section: Rate-dependent Damage and Deformation Modelmentioning

confidence: 99%

“…Extending the theory of rate processes, Ghoniem, Matthews and Amodeo (GMA) [2] were able to formulate a comprehensive theory of radiation-induced defect and dislocation microstructure evolution. Their dislocation-based creep model was initially developed to predict high-temperature deformation under arbitrary time-dependent stress and temperature histories for engineering materials.…”

Section: Rate-dependent Damage and Deformation Modelmentioning

confidence: 99%

“…This dislocation-based constitutive model is composed of six rate equations to predict the behavior of six engineering parameters, namely the creep strain, the mobile, static and boundary dislocation density, the average sub-grain radius, and the applied stress. The overall model can be summarized in the following equations [2]:…”

Section: Rate-dependent Damage and Deformation Modelmentioning

confidence: 99%

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Proposed damage evolution model for large-scale finite element modeling of the dual coolant US-ITER TBM

Sharafat¹,

El‐Awady²,

Liu³

et al. 2007

Journal of Nuclear Materials

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“…A brief review of some of the models is given here. Ghoniem et al [25] developed a model for creep (GMA model) based on unit dislocation evolution mechanisms. This model can be integrated with rate theorybased evolution of point defects in irradiated materials.…”

Section: Summary Of Prior Constitutive Modelling Effortsmentioning

confidence: 99%

Crystal plasticity-based constitutive modelling of irradiated bcc structures

Patra

2012

Philosophical Magazine

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A constitutive crystal plasticity model is proposed and developed for the inelastic deformation of irradiated bcc ferritic/martensitic steels. Defects found in these irradiated materials are used as substructure variables in the model. Insights from lower length-and time-scale simulations are used to frame the kinematic and substructure evolution relations of the governing deformation mechanisms. Models for evolution of mobile and immobile dislocations, as well as interstitial loops (formed due to irradiation), are developed. A rate theory-based approach is used to model the evolution of point defects generated during irradiation. The model is used to simulate the quasi-static tensile and creep response of a martensitic steel over a range of loading histories.

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Numerical Simulation 0f Dislocation Patterns during Plastic Deformation

Cited by 15 publications

References 40 publications

On Dislocation Patterning: Revisiting the W-A Model Part I: The Role of Gradient Terms in Dislocation Dynamics

On Dislocation Patterning: Revisiting the W-A Model Part I: The Role of Gradient Terms in Dislocation Dynamics

Proposed damage evolution model for large-scale finite element modeling of the dual coolant US-ITER TBM

Crystal plasticity-based constitutive modelling of irradiated bcc structures

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