Multiple slip dislocation patterning in a dislocation-based crystal plasticity finite element method

Grilli, Nicolò; Janssens, Maddy; Nellessen, Jens; Sandlöbes, Stefanie; Raabe, Dierk

doi:10.1016/j.ijplas.2017.09.015

Cited by 63 publications

(32 citation statements)

References 52 publications

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“…where 1 y and 2 y are the concentrations of the reacting species, 3 y are the concentration of the product, c is the reaction constant. Equation (28) shows that the effect on the instantaneous rate of change is proportional to the product of the concentrations of the reacting species, see [23,46].…”

Section: Junction Reactions In Addition To Dislocation Transportmentioning

confidence: 99%

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Implementation of annihilation and junction reactions in vector density-based continuum dislocation dynamics

Lin

El–Azab

2020

Modelling Simul. Mater. Sci. Eng.

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In a continuum dislocation dynamics formulation by Xia and El-Azab [1], dislocations are represented by a set of vector density fields, one per crystallographic slip systems. The space-time evolution of these densities is obtained by solving a set of dislocation transport equations coupled with crystal mechanics. Here, we present an approach for incorporating dislocation annihilation and junction reactions into the dislocation transport equations. These reactions consume dislocations and result in nothing as in the annihilation reactions, or produce new dislocations of different types as in the case of junction reactions. Collinear annihilation, glissile junctions, and sessile junctions are particularly emphasized here. A generalized energy-based criterion for junction reactions is established in terms of the dislocation density and Burgers vectors of the reacting species, and the reaction rate terms for junction reactions are formulated in terms of the dislocation densities. In order to illustrate how the dislocation network changes as a result of junction formation and annihilation in a continuum dislocation dynamics setting, we present some numerical examples focusing on the reactions processes themselves. The results show that our modeling approach is able to capture the respective dislocation network changes associated with dislocation reactions: dislocations of opposite line directions encountering each other on collinear slip systems annihilate to connect the dislocations on the two slip systems, glissile junctions form on new slip system behave like Frank-Read sources, and sessile junctions form and expand along the intersection of the slip planes of the reacting dislocation species. A collective-dynamics test showing the frequency of occurrence of junctions of different types relative to each other is also presented.

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Section: Junction Reactions In Addition To Dislocation Transportmentioning

confidence: 99%

“…In this case, c represents the junction reaction rate, which should be derived by coarse-graining data from discrete dislocation dynamic simulations, see, for example, see [46]. Finally, based on equations (28) and (29), the amount of glissile junction form, (1,2) junc   , can be derived as…”

Section: Junction Reactions In Addition To Dislocation Transportmentioning

confidence: 99%

Implementation of annihilation and junction reactions in vector density-based continuum dislocation dynamics

Lin

El–Azab

2020

Modelling Simul. Mater. Sci. Eng.

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“…These physical phenomena are the deformation-twin thickening, dynamic/static pinning of dislocations, strain-path change, tension-compression asymmetry, slip transfer at microstructural interfaces and, most importantly, damage and fracture. Computationally expensive but advanced (continuum) gradient-based crystal plasticity constitutive models with dislocation fluxes 94,95 that are coupled with phase field models for damage 96 and twinning 97 can be used to inform/improve the applied more efficient model. Properties-performance PP link the model used for performance simulation takes the flow curves corresponding to different deformation parameters (combination of strain rate, temperature and loading axis) as input.…”

Section: Remaining Challengesmentioning

confidence: 99%

Optimal Design for Metal Additive Manufacturing: An Integrated Computational Materials Engineering (ICME) Approach

Motaman

Kies

Köhnen

et al. 2020

JOM

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We present our latest results on linking the process-structure-propertiesperformance (PSPP) chain for metal additive manufacturing (AM), using a multi-scale and multi-physics integrated computational materials engineering (ICME) approach. The abundance of design parameters and the complex relationship between those and the performance of AM parts have so far impeded the widespread adoption of metal AM technologies for structurally critical load-bearing components. To unfold the full potential of metal AM, establishing a full quantitative PSPP linkage is essential. It will not only help in understanding the underlying physics but will also serve as a powerful and effective tool for optimal computational design. In this work, we illustrate an example of ICME-based PSPP linkage in metal AM, along with a hybrid physics-based data-driven strategy for its application in the optimal design of a component. Finally, we discuss our outlook for the improvement of each part in the computational linking of the PSPP chain.

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“…A sessile dislocation junction forms when a glissile dislocation cuts through a forest dislocation that does not lie on the same slip plane. This mechanism contributes to the formation of complex, tangled dislocation arrays during crystal deformation (Grilli et al, 2018), and is a key source of strain hardening. Given their importance, dislocation junctions have been extensively studied .…”

Section: Introductionmentioning

confidence: 99%

Influence of hydrogen core force shielding on dislocation junctions in iron

Katzarov

Paxton

et al. 2020

Phys. Rev. Materials

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The influence of hydrogen on dislocation junctions was analysed by incorporating a hydrogen dependent core force into nodal based discrete dislocation dynamics. Hydrogen reduces the core energy of dislocations, which reduces the magnitude of the dislocation core force. We refer to this as hydrogen core force shielding, as it is analogous to hydrogen elastic shielding but occurs at much lower hydrogen concentrations. The dislocation core energy change due to hydrogen was calibrated at the atomic scale accounting for the nonlinear inter-atomic interactions at the dislocation core, giving the model a sound physical basis. Hydrogen was found to strengthen binary junctions and promote the nucleation of dislocations from triple junctions. Simulations of microcantilever bend tests with hydrogen core force shielding showed an increase in the junction density and subsequent hardening. These simulations were performed at a small hydrogen concentration realistic for bcc iron.

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Multiple slip dislocation patterning in a dislocation-based crystal plasticity finite element method

Cited by 63 publications

References 52 publications

Implementation of annihilation and junction reactions in vector density-based continuum dislocation dynamics

Implementation of annihilation and junction reactions in vector density-based continuum dislocation dynamics

Optimal Design for Metal Additive Manufacturing: An Integrated Computational Materials Engineering (ICME) Approach

Influence of hydrogen core force shielding on dislocation junctions in iron

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