Article
Engineering, Mechanical
Kyle Starkey, Anter El-Azab
Summary: We propose a computational algorithm for solving the finite-deformation continuum dislocation dynamics theory and demonstrate its effectiveness through various test problems.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Materials Science, Multidisciplinary
Abhishek Arora, Rajat Arora, Amit Acharya
Summary: This study demonstrates the significantly different responses of metal thin films in compression and shear, and successfully simulates this behavior using the Mesoscale Field Dislocation Mechanics (MFDM) model without any modification or additional fitting parameters. This research represents a crucial theoretical advancement in the field of strain gradient plasticity models.
Article
Materials Science, Multidisciplinary
Nilgoon Irani, Yaswanth Murugesan, Can Ayas, Lucia Nicola
Summary: Discrete dislocation plasticity is a modeling technique that treats plasticity as the collective motion of dislocations, with the core fields affecting edge dislocation interactions. Simulation results show that the influence of core fields is negligible compared to Volterra fields or external loads.
MECHANICS OF MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Vignesh Vivekanandan, Peng Lin, Grethe Winther, Anter El-Azab
Summary: The continuum dislocation dynamics framework aims to capture the evolution of dislocation density and deformation of crystals under mechanical loading by solving transport equations for dislocations concurrently with crystal mechanics equations, incorporating dislocation reactions to improve predictability. The proposed formulation, which includes virtual dislocations to enforce dislocation line continuity, enables accurate enforcement of divergence free condition in numerical solutions, leading to highly accurate results in comparison with previous approaches.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2021)
Article
Engineering, Mechanical
Shahram Dindarlou, Gustavo M. Castelluccio
Summary: This study presents a novel crystal plasticity model based on mesoscale dislocation substructures for predicting the response of materials with similar dislocation substructures. By using a unique set of parameters with known uncertainty, the model successfully reproduces the mechanical response of FCC single-and poly-crystals. The model's effectiveness is further validated by comparing it to experimental results.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Engineering, Mechanical
F. Bahrami, M. Hammad, M. Fivel, B. Huet, C. D'Haese, L. Ding, B. Nysten, H. Idrissi, J. P. Raskin, T. Pardoen
Summary: Graphene reinforcement has been studied for its impact on the mechanical properties of metals, showing earlier and shorter plastic indentation responses compared to systems without graphene. Atomic force microscopy reveals smoother pile-ups with graphene, while transmission electron microscopy shows more diffuse and homogeneous dislocation activity in the presence of graphene. The collective dislocation mechanisms are dominantly controlled by the strong back stress caused by the graphene barrier.
INTERNATIONAL JOURNAL OF PLASTICITY
(2021)
Article
Engineering, Mechanical
Yinan Cui, Tao Wang, Shichao Luo, Zhangtao Li, Zhijie Li
Summary: Understanding the deformation mechanism of materials at extremely high strain rates is crucial. In this study, a discrete-continuous model coupling three-dimensional discrete dislocation elastodynamics with the finite element method was developed, successfully reproducing the fully-resolved elastodynamic field of non-uniformly moving dislocations and revealing intriguing features of high-speed dislocations. This work provides an exciting opportunity to comprehend the collective behavior of high-speed dislocations under complex shock loading conditions.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Materials Science, Multidisciplinary
Xi Luo, Michael Zaiser
Summary: Continuum dislocation dynamics (CDD) describes the evolution of curved and connected dislocation lines using density-like field variables, including the volume density of loops as an additional field. The curvature field evolution equation contains numerically inconvenient higher-order derivatives of the density fields, as dislocation curvature represents a spatial derivative of the discrete dislocation density tensor. We propose a simple approximation to express curvature in terms of density fields and demonstrate its application to a benchmark problem in Mg polycrystal deformation.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2023)
Article
Nanoscience & Nanotechnology
Fabrizio Rovaris, Stefanos Papanikolaou, Mikko J. Alava
Summary: This study investigates the effect of small curvature on dislocation mechanisms in uniaxial compression of micropillars using Finite Element and Discrete Dislocation Dynamics simulations. The results indicate that small curvature leads to significant dynamical effects on dislocation mechanisms and overestimate of strain at yielding. This results in large errors in capturing elastic compression moduli and avalanche noise characteristics.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Peng Wang, Daoxuan Zhou, Haoran Zhao, Yicheng Lin, Anmin Nie, Hongtao Wang
Summary: Recent experimental findings have confirmed the occurrence of dislocation gliding and the activation of the {001}<110> slip system in single-crystal diamond at room temperature. However, there is limited theoretical research and simulation on this dislocation gliding in the {001}<110> slip system. In this study, a new potential function called the Tersoff High Pressure potential is derived from the original Tersoff potential, and it includes a novel bond order term with the nearest neighbors. Molecular dynamic simulations of both {001}<110> and {111}<110> dislocation slip systems in diamond validate this model, successfully explaining the dislocation mediated transition from brittle to ductile behavior under high hydrostatic pressure. The current model is expected to be useful for studying the strengthening mechanism in diamond and conducting related research.
DIAMOND AND RELATED MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Balduin Katzer, Kolja Zoller, Daniel Weygand, Katrin Schulz
Summary: Plastic deformation of metals involves the formation and evolution of complex dislocation networks, which are crucial for the development of crystal plasticity models. This study demonstrates the transfer of knowledge from discrete dislocation dynamics simulations to continuum-based models through a physically based dislocation network evolution theory. The results show that the evolution of dislocation networks is influenced by crystal orientation and the activity of slip systems.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2022)
Article
Chemistry, Physical
Fei Shuang, Katerina E. Aifantis
Summary: This study investigates the interaction mechanisms between graphene nanosheets (GNS) and dislocations using Molecular Dynamics (MD) simulations. The results show that the shear strength of the metal/GNS interface and the bending stiffness of GNS play significant roles in blocking dislocation transmission. The mechanical interface energy is proposed as a unified measure for capturing and tuning the strength of various interfaces.
APPLIED SURFACE SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Aytekin Demirci, Dominik Steinberger, Markus Stricker, Nina Merkert, Daniel Weygand, Stefan Sandfeld
Summary: Discrete dislocation dynamics simulations have been proven to accurately predict the evolution of dislocation microstructures for metallic samples at the micrometer scale. This study focuses on analyzing the influence of cross-slip on the evolution of dislocation systems. A data mining strategy using the 'discrete-to-continuous (D2C) framework' is employed to quantify differences and compare dislocation structures. The effects of cross-slip on microstructure evolution are analyzed during a tensile test and subsequent relaxation.
MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING
(2023)
Article
Engineering, Mechanical
Wenbo Dong, Hengjie Liu, Juan Du, Xu Zhang, Minsheng Huang, Zhenhuan Li, Ziguang Chen, Florin Bobaru
Summary: This paper presents a solution for discrete dislocation dynamics problems using the peridynamic-based superposition framework. The new scheme can simulate arbitrary domains without explicitly tracking boundaries and interfaces. The numerical results show that the new scheme is more accurate near dislocation cores compared to existing schemes.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Nuclear Science & Technology
Pandong Lin, Junfeng Nie, Meidan Liu
Summary: A multiscale crystal plasticity finite element model, incorporating molecular dynamics and crystal plasticity theory, is proposed to analyze the mechanical behavior of irradiated BCC metals. The numerical results agree well with experimental data, demonstrating the accuracy and feasibility of the model. The model captures irradiation hardening and provides a theoretical guide for selecting structural materials in nuclear plants.
NUCLEAR MATERIALS AND ENERGY
(2022)
Review
Biochemistry & Molecular Biology
Rui Martim Salgado, Federico Danzi, Joana Espain Oliveira, Anter El-Azab, Pedro Ponces Camanho, Maria Helena Braga
Summary: Global energy demand is growing rapidly due to population and economic growth, especially in large emerging countries. Electric vehicles are playing a crucial role in the electrification revolution to reduce carbon emissions. Major trends in Li-ion battery technologies for EVs include material selection, electrolytes, and future development directions.
Article
Nanoscience & Nanotechnology
J. Lu, R. L. Paldi, Y. Pachaury, D. Zhang, Han Wang, M. Kalaswad, X. Sun, J. Liu, X. L. Phuah, X. Zhang, A. A. El-Azab, H. Wang
Summary: Coupled multifunctionalities in nanocomposite thin films offer a pathway toward future integration of device applications. In this work, initial success of in-plane long-range ordering achieved in a new oxide-metal VAN system demonstrates multifunctionalities enabled by the combination of plasmonic Au and ferromagnetic LSMO.
MATERIALS TODAY NANO
(2021)
Article
Materials Science, Multidisciplinary
Tomohisa Kumagai, Yash Pachaury, Raven Maccione, Janelle Wharry, Anter El-Azab
Summary: The study investigated the edge, screw, and mixed dislocation velocities in FeCrAl body-centered cubic alloy for the <111> {110} type slip system through classical molecular dynamics simulation. Different behaviors were observed for dislocations in screw, edge, and mixed orientations with applied shear stress, including zero velocity below a threshold stress, slow glide regime, linear regime, and nonlinear regime. The study also found that the rate of increase of the dislocation velocity decreases with chromium and aluminum concentrations, and the dependence of the velocity on the angle between the Burgers vector direction and the dislocation line direction follows a sinusoidal-like behavior.
Article
Materials Science, Multidisciplinary
Kyle Starkey, Ahmad Ahmad, Juanjuan Lu, Haiyan Wang, Anter El-Azab
Summary: In recent years, functional oxide-metal based vertically aligned nanocomposite (VAN) thin films have attracted attention due to their complex interactions and multifunctional properties. This study presents a model for analyzing the energetics of these thin film systems, considering lattice mismatch and capillary forces caused by interface curvature. The results show that random configurations of pillar structures have the lowest total energy, and interfacial energy plays a dominant role in the system.
Review
Chemistry, Multidisciplinary
David H. Hurley, Anter El-Azab, Matthew S. Bryan, Michael W. D. Cooper, Cody A. Dennett, Krzysztof Gofryk, Lingfeng He, Marat Khafizov, Gerard H. Lander, Michael E. Manley, J. Matthew Mann, Chris A. Marianetti, Karl Rickert, Farida A. Selim, Michael R. Tonks, Janelle P. Wharry
Summary: Efforts to understand and control thermal transport in nuclear fuels have advanced with the introduction of new tools, although challenges remain in developing comprehensive models for predicting thermal energy transport in varying environmental conditions.
Article
Physics, Applied
Jie Peng, W. Ryan Deskins, Linu Malakkal, Anter El-Azab
Summary: A theoretical model for the thermal conductivity of alpha-U was developed, combining density functional theory calculations and the electron-phonon Boltzmann transport equation. The model incorporates both electron and phonon contributions to thermal conductivity and shows good agreement with experimental data. It examines the dominant scattering mechanism governing thermal transport in alpha-U at different temperatures and studies the impact of point defects on the thermal conductivity.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Peng Lin, Vignesh Vivekanandan, Benjamin Anglin, Clint Geller, Anter El-Azab
Summary: The detailed model for jog formation and transport during plastic deformation of crystalline materials was developed within the vector density-based continuum dislocation dynamics framework, with a focus on the balance equations for point defect generation associated with jog transport. Results showed an asymmetry in vacancy and interstitial generation, and coupling the point defect generation mechanism to dislocation dynamics led to a higher hardening rate and dislocation density.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2021)
Article
Materials Science, Multidisciplinary
Kyle Starkey, Thomas Hochrainer, Anter El-Azab
Summary: This work presents how the evolution of dislocation networks and their reactions are introduced into continuum dislocation models. By leveraging de Rham currents theory and Frank's second rule, the study ensures that the structure of the dislocation network satisfies classical relations. Additionally, the introduction of junction point density as a new state variable represents the distribution of junction points in the crystal.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2022)
Article
Materials Science, Multidisciplinary
Janne Pakarinen, Lingfeng He, Jian Gan, Andrew T. Nelson, Anter El-Azab, Marat Khafizov, Todd R. Allen
Summary: The effects of proton irradiation in polycrystalline UO2 were studied using SEM and TEM, revealing that implanted H+ formed two-dimensional cavities on the surface instead of diffusing into the matrix, leading to surface flaking and blistering, supporting previous studies on crystalline materials.
Article
Materials Science, Multidisciplinary
Yash Pachaury, Giacomo Po, Anter El-Azab
Summary: A novel implementation of the dislocation flux boundary condition in discrete dislocation dynamics is presented, where the continuity of individual dislocation loops in a periodic representative crystal volume is enforced across the boundary with the help of a dual topological description. The implementation details are discussed in the context of statistical homogeneity of bulk crystals undergoing macroscopically homogeneous plastic deformation.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2022)
Article
Materials Science, Multidisciplinary
Vignesh Vivekanandan, Joseph Pierre Anderson, Yash Pachaury, Mamdouh S. Mohamed, Anter El-Azab
Summary: The study presents a statistical analysis of internal stress fluctuations in deforming crystals with 3D discrete dislocation systems, revealing that Schmid and Escaig stress fluctuations follow a Cauchy distribution at all strain levels, with the amplitude and width of the distribution dependent on the strain. The implications of these internal stress fluctuations are discussed from the perspectives of dislocation cross-slip and dislocation motion in continuum dislocation dynamics.
MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING
(2022)
Article
Biochemistry & Molecular Biology
Robynne L. Paldi, Juanjuan Lu, Yash Pachaury, Zihao He, Nirali A. Bhatt, Xinghang Zhang, Anter El-Azab, Aleem Siddiqui, Haiyan Wang
Summary: Hyperbolic metamaterials exhibit anisotropic dielectric function and have applications in subdiffraction imaging and hyperlenses. In this study, self-assembled plasmonic metamaterials consisting of anisotropic nanoalloy pillars embedded into the ZnO matrix were developed using a seed-layer approach. The ZnO-AuxCu1-x system demonstrated excellent epitaxial quality and optical properties compared with the ZnO-AuxAl1-x system.
Article
Nanoscience & Nanotechnology
Chao Yang, Yash Pachaury, Anter El-Azab, Janelle Wharry
Summary: Vacancies have no significant effect on martensitic transformation, while voids activate the transformation by inducing shear strain accumulation due to dislocation pileup. The larger the void, the more pronounced the effect.
SCRIPTA MATERIALIA
(2022)
Article
Materials Science, Multidisciplinary
Rayaprolu Goutham Sreekar Annadanam, Cuncai Fan, Tongjun Niu, Xinghang Zhang, Anter El-Azab
Summary: We propose a previously unreported mechanism for the removal of SFT in irradiated copper, which involves the conversion of SFTs to helium bubbles under the influence of helium-induced shear stress.
COMPUTATIONAL MATERIALS SCIENCE
(2022)
Article
Engineering, Mechanical
Kyle Starkey, Anter El-Azab
Summary: We propose a computational algorithm for solving the finite-deformation continuum dislocation dynamics theory and demonstrate its effectiveness through various test problems.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)