Bibliografias temáticas / Discrete dislocation

Literatura científica selecionada sobre o tema "Discrete dislocation"

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Publicado: 25 de maio de 2024

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Artigos de revistas sobre o assunto "Discrete dislocation"

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Diop, Mouhamadou, Hai Hao, Han Wei Dong e Xing Guo Zhang. "Simulation of Discrete Dislocation Statics and Dynamics of Magnesium Foam". Materials Science Forum 675-677 (fevereiro de 2011): 929–32. http://dx.doi.org/10.4028/www.scientific.net/msf.675-677.929.

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The simulation of magnesium plasticity at the microscopic and mesoscopic scale using space and time-discretized statics and dynamics dislocation was carried out. The complexity of discrete dislocation models dues to the fact that the mechanical interaction of ensembles of such defects is with an elastic nature, and therefore involves long-range interactions. The motion of dislocations or dislocation segments in their respective glide planes are usually described by assuming simple phenomenological viscous flows laws. The formulation of the dislocation dynamics is obtained by the Newton’s Second Law of motion for each dislocation or dislocation segment. The evolution of the dislocation position is obtained by simple difference algorithms.
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Záležák, Tomáš, e Antonín Dlouhý. "3D Discrete Dislocation Modelling of High Temperature Plasticity". Key Engineering Materials 465 (janeiro de 2011): 115–18. http://dx.doi.org/10.4028/www.scientific.net/kem.465.115.

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A 3D model is presented that addresses an evolution of flexible dislocation lines at high temperatures. The model is based on the linear theory of elasticity. A smooth dislocation line is approximated by a piecewise curve composed of short straight dislocation segments. Each dislocation segment is acted upon by a Peach-Koehler force due to a local stress field. All segment-segment interactions as well as an externally applied stress are considered. A segment mobility is proportional to the Peach-Koehler force, temperature-dependent factors control climb and glide motion of the segments. The potential of the model is demonstrated in simulations of simple high temperature processes including interactions of dislocations with secondary particles.
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Li, Luo, e Tariq Khraishi. "An Investigation of Spiral Dislocation Sources Using Discrete Dislocation Dynamics (DDD) Simulations". Metals 13, n.º 8 (6 de agosto de 2023): 1408. http://dx.doi.org/10.3390/met13081408.

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Discrete Dislocation Dynamics (DDD) simulations are a powerful simulation methodology that can predict a crystalline material’s constitutive behavior based on its loading conditions and micro-constituent population/distribution. In this paper, a 3D DDD model with spiral dislocation sources is developed to study size-dependent plasticity in a pure metal material (taken here as Aluminum). It also shows, for the first time, multipole simulations of spirals and how they interact with one another. In addition, this paper also discusses how the free surface of a crystalline material affects the plasticity generation of the spiral dislocation. The surface effect is implemented using the Distributed Dislocation Method. One of the main results from this work, shown here for the first time, is that spiral dislocations can result in traditional Frank–Read sources (edge or screw character) in a crystal. Another important result from this paper is that with more dislocation sources, the plastic flow inside the material is more continuous, which results in a lowering of the flow stress. Lastly, the multipole interaction of the spiral dislocations resulted in a steady-state fan-shaped action for these dislocation sources.
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Huang, C. C., C. C. Yu e Sanboh Lee. "The behavior of screw dislocations dynamically emitted from the tip of a surface crack during loading and unloading". Journal of Materials Research 10, n.º 1 (janeiro de 1995): 183–89. http://dx.doi.org/10.1557/jmr.1995.0183.

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The behavior of screw dislocations dynamically emitted from the tip of a surface crack during loading and unloading has been investigated using a discrete dislocation model. The critical stress intensity factor at the crack tip for dislocation emission is a function of friction stress, core radius of dislocation, and dislocations near the crack tip. During motion, the velocity of dislocation is assumed to be proportional to the effective shear stress to the third power. The effect of crack length and friction stress on dislocation distributions, plastic zone, and dislocation-free zone during loading and unloading was examined.
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Mastorakos, Ioannis N., Firas E. Akasheh e Hussein M. Zbib. "Treating internal surfaces and interfaces in discrete dislocation dynamics". Journal of the Mechanical Behaviour of Materials 20, n.º 1-3 (1 de dezembro de 2011): 13–20. http://dx.doi.org/10.1515/jmbm.2011.002.

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AbstractThe treatment of coherent interfaces and cracks is discussed in the framework of dislocation dynamics (DD). In the case of interfaces, we use DD to study dislocation interactions in nanoscale bimetallic laminates, and to predict their structure after relaxation and during loading. In agreement with experimental observations, our discrete dynamics simulations show that dislocation structure develops only at the interface between coherent layers leaving layers’ interior dislocation-free. The main dislocation mechanism at this length scale is Oworan bowing of threading dislocations confined to their respective layers by the sign-alternating coherency stress field in the layers. Slip transmission across the interfaces marks the end of the confined slip regime, hence, the breakdown of the interfaces and macroscopic yielding of these structures. In the case of crack, its long-range and singular stress field is determined by modeling the crack as continuous distribution of dislocation loops. The traction boundary condition to be satisfied at the crack surface, results into a singular integral equation of the first kind that is solved numerically. The model is integrated with the DD technique to investigate the behavior of a specimen containing cracks of different shapes under fatigue. The results are compared with the behavior of an uncracked specimen and conclusions are extracted. Extension of this crack treatment methodology to account for their presence at interfaces, all within the frame dislocations dynamics, opens the door for a more realistic approach to a wide range of interfaces-related problems.
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Ayas, Can, e Vikram Deshpande. "Climb Enabled Discrete Dislocation Plasticity of Superalloys". Key Engineering Materials 651-653 (julho de 2015): 981–86. http://dx.doi.org/10.4028/www.scientific.net/kem.651-653.981.

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Ni-based superalloys comprising of elastic particles embedded in a single crystal elastic-plastic matrix are usually subject to loading at elevated service temperatures. In order to enhance the understanding of high temperature deformation mechanisms a two dimensional discrete dislocation plasticity framework wherein the dislocations movement that incorporates both glide and climb is formulated. The climbing dislocations are modelled as point sources/sinks of vacancies and the vacancy diffusion boundary value problem is solved by superposition of the vacancy concentration fields of the point sources/sinks in an infinite medium and a complementary non-singular solution that enforces the relevant boundary conditions. The vacancy concentration field along with the Peach-Kohler force provides the climb rate of the dislocations.
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Needleman, Alan, e E. Van der Giessen. "Discrete Dislocation Plasticity". Key Engineering Materials 233-236 (janeiro de 2003): 13–24. http://dx.doi.org/10.4028/www.scientific.net/kem.233-236.13.

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Stricker, Markus, Michael Ziemann, Mario Walter, Sabine M. Weygand, Patric Gruber e Daniel Weygand. "Dislocation structure analysis in the strain gradient of torsion loading: a comparison between modelling and experiment". Modelling and Simulation in Materials Science and Engineering 30, n.º 3 (8 de fevereiro de 2022): 035007. http://dx.doi.org/10.1088/1361-651x/ac4d77.

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Abstract Complex stress states due to torsion lead to dislocation structures characteristic for the chosen torsion axis. The formation mechanism of these structures and the link to the overall plastic deformation are unclear. Experiments allow the analysis of cross sections only ex situ or are limited in spacial resolution which prohibits the identification of the substructures which form within the volume. Discrete dislocation dynamics simulations give full access to the dislocation structure and their evolution in time. By combining both approaches and comparing similar measures the dislocation structure formation in torsion loading of micro wires is explained. For the ⟨100⟩ torsion axis, slip traces spanning the entire sample in both simulation and experiment are observed. They are caused by collective motion of dislocations on adjacent slip planes. Thus these slip traces are not atomically sharp. Torsion loading around a ⟨111⟩ axis favors plasticity on the primary slip planes perpendicular to the torsion axis and dislocation storage through cross-slip and subsequent collinear junction formation. Resulting hexagonal dislocation networks patches are small angle grain boundaries. Both, experiments and discrete dislocation simulations show that dislocations cross the neutral fiber. This feature is discussed in light of the limits of continuum descriptions of plasticity.
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Zbib, Hussein M., Tomas Diaz de la Rubia e Vasily Bulatov. "A Multiscale Model of Plasticity Based on Discrete Dislocation Dynamics". Journal of Engineering Materials and Technology 124, n.º 1 (28 de maio de 2001): 78–87. http://dx.doi.org/10.1115/1.1421351.

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We present a framework coupling continuum elasto-viscoplasticity with three-dimensional discrete dislocation dynamics. In this approach, the elastic response is governed by the classical Hooke’s law and the viscoplastic behavior is determined by the motion of curved dislocations in a three-dimensional space. The resulting hybrid continuum-discrete framework is formulated into a standard finite element model where the dislocation-induced stress is homogenized over each element with a similar treatment for the dislocation-induced plastic strain. The model can be used to investigate a wide range of small scale plasticity phenomena, including microshear bands, adiabatic shear bands, stability and formation of dislocation cells, thin films and multiplayer structures. Here we present results pertaining to the formation of deformation bands and surface distortions under dynamic loading conditions and show the capability of the model in analyzing complicated deformation-induced patterns.
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Holec, David, e Antonín Dlouhý. "Stability and Motion of Low Angle Dislocation Boundaries in Precipitation Hardened Crystals". Materials Science Forum 482 (abril de 2005): 159–62. http://dx.doi.org/10.4028/www.scientific.net/msf.482.159.

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The present study investigates stability and motion of low angle dislocation boundaries in an array of precipitates. The model considers discrete dislocations and precipitates that are treated as impenetrable particles. Peach-Koehler forces, which originate due to the combined effect of dislocation-dislocation interactions and the applied stress, act the individual dislocations on. Both, the dislocation glide and the dislocation climb at elevated temperatures are taken into account. Results of the numerical study suggest that a critical applied shear stress (CASS) always exists which separates stable and unstable low angle boundary configurations. Varying particle size, interparticle spacing and density of dislocations in the boundary cause changes of the CASS that are systematically investigated. It is shown that the CASSs can considerably differ from the standard Orowan stress controlling the equilibrium of an isolated dislocation in a given microstructure. This result underlines the importance of long-range dislocation interactions that influence the high temperature strength of the precipitation-hardened alloys.
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Teses / dissertações sobre o assunto "Discrete dislocation"

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Shin, Chansun. "3D discrete dislocation dynamics applied to dislocation-precipitate interactions". Grenoble INPG, 2004. http://www.theses.fr/2004INPG0116.

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La dynamique des dislocations discrètes (DDD) a été appliquée pour examiner les effets des précipités sur la plasticité des monocristaux de structure CFC. Les précipités sont modélisés par un assemblage de facettes franchissable pour une contrainte donnée. Afin de tenir compte des interactions élastiques entre les dislocations et les particules, un couplage avec la méthode des éléments finis (MEF) a été utilisé. Afin d'accélérer les temps de calculs, la 'méthode des boites' a été revisitée et une version parallèle du code a été développée en utilisant le standard du programmation 'Message Passing Interface (MPI)'. Dans un premier temps, les contraintes images créées par une particule 3D ont été calculées grâce un couplage entre la MEF et le code de DDD. Les résultats numériques ont été comparés aux solutions analytiques correspondantes. L'effet de la différence des modules d'Young sur la limite élastique et le comportement durcissant qui en découle ont ensuite été étudiés numériquement. Nous avons montré que les contraintes image ont un effet significatif sur le durcissement et les événements locaux tels que le glissement dévié et la montée. Finalement, la fatigue des matériaux durcis par des précipités cisaillables et non-cisaillables a été simulée avec le nouveau code parallèle de DDD. Les résultats obtenus grâce à nos simulations sont en accord avec nos observations experimentales et les données de la littérature. Un mécanisme de formation des bandes de glissement intense a été proposé à partir de l'observation des microstructures obtenues par simulation
The 3D Discrete Dislocation Dynamics (DDD) method has been applied to investigate the effects of precipitates on the plasticity of FCC single crystals. A method to represent the internal interfaces by a series of facets with a pre-defined strength has been proposed. For a full account of the mutual elastic interactions between dislocations and second-phase particles, the coupling method with a finite element method is extended. In order to accelerate the computing time, the serial 3D DDD algorithm has been improved by revisiting the 'box method' and a new parallel code has been developed using the standard Message passing Interface (MPI). The image stresses due to a three-dimensional particle were computed using the FEM/DDD coupling code. The numerical results have been compared to the corresponding analytical solutions. The effect of the elastic modulus mismatch on the flow stress and the subsequent hardening behavior has then been analyzed. The image stresses were found to affect significantly the work hardening and the local events such as cross slip and climb. Finally, the fatigue of precipitate-hardened materials was simulated using the new parallel DDD code. The effects of shearable and non-shearable particles on the fatigue properties were well reproduced by the simulations, and the numerical results showed good agreements with the available experimental observations in a qualitative way. The mechanism of the intense slip band formation is proposed from the observation of the simulated dislocation microstructure
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Liu, Bing [Verfasser]. "Discrete dislocation dynamics simulations of dislocation : low angle grain boundary interactions / Bing Liu". Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2012. http://d-nb.info/1027743900/34.

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Mohammad, Davoudi Kamyar. "Plastic Behavior of Polycrytalline Thin Films: Discrete Dislocation Study". Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11634.

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Explaining the work-hardening behavior of crystalline materials and the size dependent plasticity has been a long lasting problem. Plastic deformation mainly arises from the collective motion of dislocations. Although individual dislocation processes are well studied, the study of the overall effects of these processes was challenging before the emergence of computer modeling. Of the computer simulation techniques, discrete dislocation dynamics (DDD) is the most suitable method to model thin films at the micron scale and below. This method allows us to study the quantitative effects of certain mechanisms.
Engineering and Applied Sciences
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Hosseinzadeh, Delandar Arash. "Numerical Modeling of Plasticity in FCC Crystalline Materials Using Discrete Dislocation Dynamics". Licentiate thesis, KTH, Materialteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-175424.

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Plasticity in crystalline solids is controlled by the microscopic line defects known as “dislocations”. Decisive role of dislocations in crystal plasticity in addition to fundamentals of plastic deformation are presented in the current thesis work. Moreover, major features of numerical modeling method “Discrete Dislocation Dynamics (DDD)” technique are described to elucidate a powerful computational method used in simulation of crystal plasticity. First part of the work is focused on the investigation of strain rate effect on the dynamic deformation of crystalline solids. Single crystal copper is chosen as a model crystal and discrete dislocation dynamics method is used to perform numerical uniaxial tensile test on the single crystal at various high strain rates. Twenty four straight dislocations of mixed character are randomly distributed inside a model crystal with an edge length of 1 µm subjected to periodic boundary conditions. Loading of the model crystal with the considered initial dislocation microstructure at constant strain rates ranging from 103 to 105s1 leads to a significant strain rate sensitivity of the plastic flow. In addition to the flow stress, microstructure evolution of the sample crystal demonstrates a considerable strain rate dependency. Furthermore, strain rate affects the strain induce microstructure heterogeneity such that more heterogeneous microstructure emerges as strain rate increases. Anisotropic characteristic of plasticity in single crystals is investigated in the second part of the study. Copper single crystal is selected to perform numerical tensile tests on the model crystal along two different loading directions of [001] and [111] at two high strain rates. Effect of loading orientation on the macroscopic behavior along with microstructure evolution of the model crystal is examined using DDD method. Investigation of dynamic response of single crystal to the mechanical loading demonstrates a substantial effect of loading orientation on the flow stress. Furthermore, plastic anisotropy is observed in dislocation density evolution such that more dislocations are generated as straining direction of single crystal is changed from [001] to [111] axis. Likewise, strain induced microstructure heterogeneity displays the effect of loading direction such that more heterogeneous microstructure evolve as single crystal is loaded along [111] direction. Formation of slip bands and consequently localization of plastic deformation are detected as model crystal is loaded along both directions.

QC 20151015

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Gonzalez, Joa Javier Antonio. "Mesoscale dislocation simulation accounting for surfaces using the superposition method : Application to nanomechanics". Electronic Thesis or Diss., Lyon, INSA, 2022. http://www.theses.fr/2022ISAL0129.

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Les nano-objets (fils, particules, films minces) sont connus pour leurs propriétés mécaniques exceptionnelles au regard de leurs homologues massifs. Diverses techniques expérimentales (microscopie électronique à transmission ou à balayage, diffraction des rayons X) sont utilisées pour étudier les nano-objets, complétées par des approches numériques telle que la dynamique moléculaire. Bien que fournissant des détails à l'échelle atomique, la dynamique moléculaire reste limitée en termes de taille et de vitesse de déformation, ouvrant la porte à d'autres méthodes comme la dynamique des dislocations discrète. La dynamique des dislocations discrète permet de décrire l'évolution d'une population de dislocations à l’échelle du grain mais est généralement utilisée dans des ensembles quasi-infinis en utilisant des cellules de simulation particulièrement grandes ou des conditions limites périodiques. Par conséquent, la dynamique des dislocations discrète seule ne peut fournir une description physique des surfaces d’un échantillon, surfaces à l'origine de nombreux processus à l'échelle nanométrique. Cette étude vise à modéliser mieux et plus fidèlement la mécanique des nano-objets en tenant compte des interactions complexes entre les dislocations et les surfaces. Pour ce faire, un nouvel outil appelé El-Numodis a été développé. El-Numodis repose sur le couplage du code de dynamique des dislocations discrète Numodis avec le code d'éléments finis Elmer en utilisant la méthode de superposition. Nous présentons ici les étapes de développement d'El-Numodis (pilotes de couplage, forces d'image des dislocations, algorithme de nucléation, etc.) ainsi que plusieurs applications incluant des problèmes d'élasticité classiques dans lesquels des surfaces sont impliquées. A titre d'exemple, la modélisation de films minces métalliques fcc montre l'influence majeure des surfaces sur la mécanique des nano-objets. Enfin, El-Numodis est utilisé pour modéliser la mécanique de nanoparticules céramiques où la nucléation de dislocation informée de manière atomistique, combinée à la théorie de l'état de transition, permet d'étudier le rôle de la taille, température et de la vitesse de déformation sur la déformation de nanocubes de MgO
Nano-objects (wires, particles, thin films) are known for their outstanding mechanical properties when compared to their bulk counterparts. Various experimental techniques (transmission and scanning electron microscopy, X-ray diffraction) are used to investigate nano-objects, all complemented by computational approaches such as molecular dynamics. While modelling atomic-scale processes in the details, molecular dynamics is limited in terms of sample size and strain rates opening doors to other methods such as the discrete dislocation dynamics. Discrete dislocation dynamics is able to describe the evolution of a dislocation population at the mesoscale but is mostly used to describe quasi-infinite ensembles using either particularly large simulation cells or relying on periodic boundary conditions. Consequently, standalone discrete dislocation dynamics cannot provide a complete description of sample surfaces that are known to be at the roots of several nanoscale processes. This study aims at better and faithfully model the mechanics of nano-objects accounting for the complex interactions between dislocations and surfaces. For this purpose, a new tool called El-Numodis was developed. El-Numodis relies on the coupling of the discrete dislocation dynamics code Numodis with the finite elements code Elmer using the superposition method in which the stress field generated by a dislocation population is corrected at the virtual surfaces of a finite-size sample using a finite-element elastic solver. In this work, we present the main development stages of El-Numodis (coupling drivers, dislocation image forces, nucleation algorithm, etc.) as well as several applications including analytically soluble elasticity problems in which surfaces are involved. As an example, the modelling of face-centered cubic metal thin films practically demonstrates the influence of surfaces on nano-objects mechanics. Finally, El-Numodis is used to model the mechanics of ceramics nanoparticles for which atomistically-informed dislocation nucleation as combined to the transition state theory allow to investigate the role of size, temperature and strain rate on the mechanical properties of MgO nanoparticles
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Gurrutxaga, Lerma Beñat. "A dynamic discrete dislocation plasticity model for the study of plastic relaxation under shock loading". Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/42360.

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This thesis concerns with Dynamic Discrete Dislocation Plasticity (D3P), a planar method of discrete dis- location dynamics aimed at the study of plastic relaxation processes in crystalline materials subjected to weak shock loading and high strain rates. Traditionally, the study of plasticity under these condi- tions was based on experimental measurement of the macroscopic response of the material. Using these data, well-known macroscopic constitutive laws and equations of state have been formulated. However, direct simulation of dislocations as the dynamic agents of plasticity in those circumstances remains a challenge. In discrete dislocation dynamics (DDD) methods, in particular planar discrete dislocation plasticity (DDP), dislocations are modelled as discrete discontinuities in an elastic contin- uum. Current DDP and DDD methods are unable to adequately simulate plastic relaxation because they treat dislocation motion quasistatically, neglecting the time-dependent nature of the elastic fields and assuming that they instantaneously acquire the shape and magnitude predicted by elastostatics. This thesis proves that under shock loading, this assumption leads to models that invariably break causality. This thesis posits that these limitations can only be overcome with a fully time-dependent formulation of the elastic fields of dislocations. A truly dynamic formulation for the creation, annihi- lation, and nonuniform motion of straight edge dislocations is derived, extending the DDP framework to a fully elastodynamic formulation, D3P. This thesis describes the changes in paradigm that D3P poses, including retardation effects in dislocation interactions and the effect of the dislocation past history. The thesis then builds an account of all the methodological aspects of D3P that have to be modified from DDP, including mobility laws, generation rules, etc. Finally, the thesis explores the ap- plications D3P has to the study of plasticity under shock loading. It is found that, D3P elastodynamic formulation is able to explain the attenuation of the dynamic yield stress in a shock as a cumulative interference of elastic waves.
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O'Day, Michael P. "A new superposition framework for discrete dislocation plasticity : methodology and application to inhomogeneous boundary value problems /". View online version; access limited to Brown University users, 2005. http://wwwlib.umi.com/dissertations/fullcit/3174654.

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Zheng, Zebang. "Investigation of cold dwell facet fatigue in titanium alloys utilising crystal plasticity and discrete dislocation plasticity modelling techniques". Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/58233.

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The focus of this project is the mechanistic basis of the load shedding phenomenon that occurs under the dwell fatigue loading scenario. A systematic study was carried out using modelling techniques at different length scales, from atomistic simulations to discrete dislocation plasticity and crystal plasticity, to investigate the effect of crystallographic orientations, localized dislocation behaviour, material intrinsic properties and external loading environments on the dwell sensitivity. A new mechanistic formalism for incorporating thermally activated dislocation escape into discrete dislocation plasticity modelling techniques is presented. The origin of the rate-sensitive behaviour of plasticity over strain rate regimes from 〖10〗^(-5) to 〖10〗^5 s^(-1) has been assessed with reference to three key mechanisms: dislocation nucleation, time of flight (dislocation mobility) and thermally activated escape of pinned dislocations. It is shown that nucleation and dislocation mobility explain rate-sensitive behaviour for strain rates in the range 〖10〗^2 to 〖10〗^5 s^(-1) while thermally-activated dislocation escape becomes the predominant rate-controlling mechanism at low strain rates. The new thermal activation DDP model was then use to investigate the soft-hard-soft rogue grain combination which is commonly associated with load shedding in Ti-6Al, Ti-6242 and Ti-6246 alloys. The application of Stroh’s dislocation pile-up model of crack nucleation to facet fracture was quantitatively assessed. Crystal plasticity modelling has been utilised to extract the thermal activation energies for pinned dislocation escape for Ti alloys based on independent experimental data. The activation energies determined are then utilised within the polycrystalline DDP model to predict the load shedding in the aforementioned alloys. The grain morphology and grain boundary penetrability effect were also studied but the key property controlling the load shedding is argued to be the time constant of the thermal activation process relative to that of the loading. The dwell sensitivity of Ti alloys was also found to be highly related to the temperature. The load shedding was found to diminish at very low or very high temperatures and maximum peak stress increase occurs at a higher temperature for a material with high activation energy. The deformation mechanisms under dwell fatigue loading are categorised into three scenarios and discussed separately.
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Srivastava, Kinshuk [Verfasser], e P. [Akademischer Betreuer] Gumbsch. "Atomistically-informed discrete dislocation dynamics modeling of plastic flow in body-centered cubic metals / Kinshuk Srivastava. Betreuer: P. Gumbsch". Karlsruhe : KIT-Bibliothek, 2014. http://d-nb.info/1054989516/34.

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Gao, Siwen [Verfasser], Alexander [Gutachter] Hartmaier e Marc [Gutachter] Fivel. "3D discrete dislocation dynamics study on fundamental creep mechanisms in single crystal superalloys / Siwen Gao ; Gutachter: Alexander Hartmaier, Marc Fivel". Bochum : Ruhr-Universität Bochum, 2016. http://d-nb.info/1116709686/34.

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Livros sobre o assunto "Discrete dislocation"

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Cui, Yinan. The Investigation of Plastic Behavior by Discrete Dislocation Dynamics for Single Crystal Pillar at Submicron Scale. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-3032-1.

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Davoudi, Kamyar Mohammad. Plastic Behavior of Polycrytalline Thin Films: Discrete Dislocation Study. 2014.

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Cui, Yinan. Investigation of Plastic Behavior by Discrete Dislocation Dynamics for Single Crystal Pillar at Submicron Scale. Springer, 2016.

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Cui, Yinan. The Investigation of Plastic Behavior by Discrete Dislocation Dynamics for Single Crystal Pillar at Submicron Scale. Springer, 2018.

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Cui, Yinan. The Investigation of Plastic Behavior by Discrete Dislocation Dynamics for Single Crystal Pillar at Submicron Scale. Springer, 2016.

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Capítulos de livros sobre o assunto "Discrete dislocation"

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Giessen, E. "Discrete Dislocation Plasticity". In Thermodynamics, Microstructures and Plasticity, 285–300. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-010-0219-6_18.

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Giessen, E., e A. Needleman. "Discrete Dislocation Plasticity". In Handbook of Materials Modeling, 1115–31. Dordrecht: Springer Netherlands, 2005. http://dx.doi.org/10.1007/1-4020-3286-2_56.

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Giessen, Erik. "Discrete Dislocation Plasticity". In Mechanics of Microstructured Materials, 259–82. Vienna: Springer Vienna, 2004. http://dx.doi.org/10.1007/978-3-7091-2776-6_8.

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Van der Giessen, E., e A. Needleman. "Discrete Dislocation Plasticity". In Handbook of Materials Modeling, 1115–31. Dordrecht: Springer Netherlands, 2005. http://dx.doi.org/10.1007/978-1-4020-3286-8_56.

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Zbib, Hussein M. "Introduction to Discrete Dislocation Dynamics". In Generalized Continua and Dislocation Theory, 289–317. Vienna: Springer Vienna, 2012. http://dx.doi.org/10.1007/978-3-7091-1222-9_4.

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Zbib, Hussein M., Masato Hiratani e Mutasem Shehadeh. "Multiscale Discrete Dislocation Dynamics Plasticity". In Continuum Scale Simulation of Engineering Materials, 201–29. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/3527603786.ch8.

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Ariza, M. P., A. Ramasubramaniam e M. Ortiz. "Discrete Dislocation Dynamics in Crystals". In Progress in Industrial Mathematics at ECMI 2006, 387–91. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-71992-2_58.

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LeSar, Richard, e Laurent Capolungo. "Advances in Discrete Dislocation Dynamics Simulations". In Handbook of Materials Modeling, 1079–110. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-319-44677-6_85.

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Groma, I., B. Bakó e P. Balogh. "From Discrete to Continuum Dislocation Dynamics". In Microstructures, Mechanical Properties and Processes - Computer Simulation and Modelling, 22–27. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/3527606157.ch4.

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LeSar, Richard, e Laurent Capolungo. "Advances in Discrete Dislocation Dynamics Simulations". In Handbook of Materials Modeling, 1–32. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-42913-7_85-1.

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Trabalhos de conferências sobre o assunto "Discrete dislocation"

1

Tan, E. H., e L. Z. Sun. "Dislocation Dynamics Modeling for Yield Strength of Nanoscale Film Heterostructures". In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-79222.

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A novel dislocation dynamics framework is developed to simulate dislocation evolutions in thin film heterostructures at nanoscale. It is based on 3-D dislocation motion together with its physical background by adding the solid viscous effect. As the numerical simulation results demonstrate, this new model completely solves a long-standing paradoxical phenomenon with which the simulation results were dependent on dislocation-segment lengths in the classical discrete dislocation dynamics theory. The proposed model is applied to simulate the effect of dislocations on the mechanical performance of thin films. The interactions among the dislocation loop, free surface and interface are rigorously computed by decomposing this complicated problem into two relatively simple sub-problems. This model is allowed to determine the critical thickness of thin films for a surface loop to nucleate and to simulate how a surface loop evolves into two threading dislocations. Furthermore, the relationship between the film thickness and yield strength is constructed and compared with the conventional Hall-Petch relation.
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2

Yin, X., e K. Komvopoulos. "A Discrete Dislocation Plasticity Analysis of Plane-Strain Indentation of a Single-Crystal Half-Space by a Smooth and a Rough Rigid Asperity". In STLE/ASME 2010 International Joint Tribology Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ijtc2010-41155.

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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.
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3

Voskoboinikov, R. E., Anatoly S. Avilov, Sergei L. Dudarev e Laurence D. Marks. "Asymptotics in discrete dislocation pile-up modelling". In ELECTRON MICROSCOPY AND MULTISCALE MODELING- EMMM-2007: An International Conference. AIP, 2008. http://dx.doi.org/10.1063/1.2918102.

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4

Senger, J., D. Weygand, O. Kraft, P. Gumbsch, Theodore E. Simos, George Psihoyios, Ch Tsitouras e Zacharias Anastassi. "Dislocation Microstructure Evolution in Cyclically Twisted Micrometer-Sized Metallic Samples: A Discrete Dislocation Dynamics Analysis". In NUMERICAL ANALYSIS AND APPLIED MATHEMATICS ICNAAM 2011: International Conference on Numerical Analysis and Applied Mathematics. AIP, 2011. http://dx.doi.org/10.1063/1.3637919.

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Tran, H. S., H. Tummala, L. Duchene, T. Pardoen, M. Fivel e A. M. Habraken. "Quasicontinuum analysis of dislocation-coherent twin boundary interaction to provide local rules to discrete dislocation dynamics". In PROCEEDINGS OF THE INTERNATIONAL CONFERENCE OF GLOBAL NETWORK FOR INNOVATIVE TECHNOLOGY AND AWAM INTERNATIONAL CONFERENCE IN CIVIL ENGINEERING (IGNITE-AICCE’17): Sustainable Technology And Practice For Infrastructure and Community Resilience. Author(s), 2017. http://dx.doi.org/10.1063/1.5008190.

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Sandfeld, S., M. Zaiser, T. Hochrainer, Theodore E. Simos, George Psihoyios e Ch Tsitouras. "Expansion of Quasi-Discrete Dislocation Loops in the Context of a 3D Continuum Theory of Curved Dislocations". In NUMERICAL ANALYSIS AND APPLIED MATHEMATICS: International Conference on Numerical Analysis and Applied Mathematics 2009: Volume 1 and Volume 2. AIP, 2009. http://dx.doi.org/10.1063/1.3241264.

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Sandfeld, Stefan, Michael Zaiser, Theodore E. Simos, George Psihoyios, Ch Tsitouras e Zacharias Anastassi. "Preface of the Symposium on Discrete and Continuum Modeling of Dislocation Systems". In NUMERICAL ANALYSIS AND APPLIED MATHEMATICS ICNAAM 2011: International Conference on Numerical Analysis and Applied Mathematics. AIP, 2011. http://dx.doi.org/10.1063/1.3637915.

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Greer, Julia R., Ju-Young Kim e Steffen Brinckmann. "In-Situ Investigation of Plasticity at Nano-Scale". In ASME 2008 9th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2008. http://dx.doi.org/10.1115/esda2008-59117.

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Mechanical behavior of crystals is dictated by dislocation motion in response to applied force. While it is extremely difficult to directly observe the motion of individual dislocations, several correlations can be made between the microscopic stress-strain behavior and dislocation activity. Here, we present for the first time the differences observed between mechanical behavior in two fundamental types of crystals: face-centered cubic, fcc (Au, Cu, Al, Ni, etc.) and body-centered cubic, bcc (W, Cr, Mo, Nb, etc.) with sub-micron dimensions subjected to in-situ micro-compression in SEM chamber. In a striking deviation from classical mechanics, there is a significant increase in strength as crystal size is reduced to 100nm; however in gold crystals (fcc) the highest strength achieved represents 44% of its theoretical strength while in molybdenum crystals (bcc) it is only 7%. Moreover, unlike in bulk where plasticity commences in a smooth fashion, both nano-crystals exhibit numerous discrete strain bursts during plastic deformation. These remarkable differences in mechanical response of fcc and bcc crystals to uniaxial micro-compression challenge the applicability of conventional strain-hardening to nano-scale crystals. We postulate that they arise from significant differences in dislocation behavior between fcc and bcc crystals at nanoscale and serve as the fundamental reason for the observed differences in their plastic deformation. Namely, dislocation starvation is the predominant mechanism of plasticity in nano-scale fcc crystals while junction formation and subsequent hardening characterize bcc plasticity, as confirmed by the microstructural electron microscopy. Experimentally obtained stress-strain curves together with video frames during deformation and cross-sectional TEM analysis are presented, and a statistical analysis of avalanche-like strain bursts is performed for both crystals and compared with stochastic models.
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Mukherjee, Subhasis, Bite Zhou, Abhijit Dasgupta e Thomas R. Bieler. "Mechanistic Modeling of the Anisotropic Steady State Creep Response of SnAgCu Single Crystal". In ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ipack2015-48710.

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A multiscale modeling framework is proposed in this study to capture the influence of the inherent elastic anisotropy of single crystal Sn and the inherent heterogeneous microstructure of a single crystal SnAgCu (SAC) solder grain on the secondary creep response of the grain. The modeling framework treats the SAC microstructure as having several distinct length scales. The smallest length scale (Tier 0) consists of the Sn BCT lattice. The eutectic Sn-Ag micro-constituent, consisting of nanoscale Ag3Sn IMC particles embedded in the single crystal BCT Sn matrix, is termed Tier 1. The single-crystal SAC microstructure, consisting of Sn dendrites and surrounding eutectic Sn-Ag phase, is termed Tier 2. Dislocation recovery mechanisms, such as Orowan climb and detachment from nanoscale Ag3Sn particles, are found to be the rate controlling mechanisms for creep deformation in the eutectic Sn-Ag phase (Tier 1) of a SAC single crystal. The anisotropic secondary creep rate of eutectic Sn-Ag phase (Tier 1), is then modeled using the above inputs and the saturated dislocation density calculated for dominant glide systems during secondary stage of creep. Saturated dislocation density is estimated as the equilibrium saturation between three competing processes: (1) dislocation generation; (2) dislocation impediment caused by back stress from pinning of dislocations at IMCs; and (3) dislocation recovery due to climb/detachment from IMCs. Secondary creep strain rate of eutectic Sn-Ag phase in three most facile slip systems is calculated and compared against the isotropic prediction. At low stress level secondary steady state creep rate along (110)[001] system is predicted to be ten times the creep rate along (100)[0-11] system. However, at high stress level, secondary steady state creep rate along (110)[001] system is predicted to be ten thousand times the creep rate along (100)[0-11] system. The above predictions are in strong agreement with (1–4) orders of magnitude of anisotropy observed in steady state secondary creep response in SAC305 solder joints tested under identical loading conditions in experiments conducted by several authors. The above model is then combined with Eigen-strain methods and average matrix stress concepts to homogenize the load sharing between the Sn dendrites and the surrounding eutectic Ag-Sn matrix. The resulting steady state creep rates are predicted for a few discrete single crystal SAC305 specimens. Very good agreement is observed between the predicted steady state creep rate and the measured creep rates for two SAC305 single crystal specimens.
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Liu, Juan, Zhenshan Cui, Hengan Ou e Liqun Ruan. "Modeling and 2-D discrete simulation of dislocation dynamics for plastic deformation of metal". In THE 11TH INTERNATIONAL CONFERENCE ON NUMERICAL METHODS IN INDUSTRIAL FORMING PROCESSES: NUMIFORM 2013. AIP, 2013. http://dx.doi.org/10.1063/1.4806845.

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