Article
Materials Science, Multidisciplinary
Hyojung Kim, Nithin Mathew, Darby J. Luscher, Abigail Hunter
Summary: Body-Centered Cubic (BCC) metals exhibit anomalous mechanical properties attributed to asymmetric behavior of screw dislocations, resulting in deviation of Critical Resolved Shear Stress (CRSS) from the Schmid law. By utilizing Phase Field Dislocation Dynamics (PFDD) modeling, it is possible to simulate and understand the non-Schmid behavior by incorporating representative dislocation properties and different energy terms in the model. The predicted CRSS using PFDD modeling shows excellent agreement with Molecular Statics (MS) predictions.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2021)
Article
Materials Science, Multidisciplinary
Kevin Chu, Adrian Diaz, Youping Chen, Ting Zhu, David L. McDowell
Summary: This study explores the application of Concurrent Atomistic-Continuum method to model dislocation mobility in random alloys at extended length scales. The results demonstrate the elimination of spurious stresses in transition regions and accurate capture of local stress fluctuations in the dislocation core region with reduced degrees of freedom by nearly 40%.
COMPUTATIONAL MATERIALS SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Subhendu Chakraborty, Somnath Ghosh
Summary: This paper presents a method for enhancing the Helmholtz free energy density functionals in coupled crystal plasticity phase-field finite element models of fracture by considering the influence of atomic-scale, crack-tip nucleated dislocations. The proposed approach is motivated and calibrated by energy equivalence between atomistic-continuum scale models, demonstrating the significant effect of nucleated dislocations on crack evolution.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2021)
Article
Engineering, Multidisciplinary
Alexander S. Davis, Jeffrey T. Lloyd, Vinamra Agrawal
Summary: The study developed two methods within the CAC framework to simulate shock wave propagation, accurately modeling shock wave velocities and tracking wave front propagation in large-scale domains. It demonstrates the potential of the CAC method and shows how a moving window technique can be used to study highly nonlinear, transient phenomena in a multiscale framework.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2022)
Article
Materials Science, Multidisciplinary
Alexander S. Davis, Vinamra Agrawal
Summary: Coupled atomistic-continuum methods can model dynamic material behavior at a lower computational cost, but suffer from wave reflections at the interfaces. This work presents a technique to incorporate the full spectrum of phonons in the coarse-scaled regions, allowing coherent wave propagation.
COMPUTATIONAL MATERIALS SCIENCE
(2022)
Article
Computer Science, Interdisciplinary Applications
Adrian Diaz, Boyang Gu, Yang Li, Steven J. Plimpton, David L. McDowell, Youping Chen
Summary: This work presents a parallel algorithm for the Concurrent Atomistic Continuum (CAC) formulation that can be integrated into existing molecular dynamics codes. The algorithm is shown to offer good agreement with MD-only models in verification benchmarks, demonstrating its efficiency in simulating systems represented by both atoms and finite elements.
JOURNAL OF COMPUTATIONAL PHYSICS
(2022)
Article
Engineering, Multidisciplinary
Patrick Wurm, Manfred H. Ulz
Summary: A new hybrid static-dynamic continuum model is proposed, combining the advantages of both dynamic and quasi-static approaches while potentially removing their drawbacks. Limited to linear elastic continua, this approach is an innovative superposition of a dynamic and a quasi-static subproblem, demonstrated through three numerical examples.
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING
(2021)
Article
Materials Science, Multidisciplinary
Alexander Dahlstrom, Frederic Danoix, Peter Hedstrom, Joakim Odqvist, Helena Zapolsky
Summary: The study found that the magnitude of stress and the crystallographic direction directly affect the development of spinodal decomposition and nanostructure morphology. The modulated nanostructure of binary bcc alloy system can be quantified by a characteristic wavelength λ. The effect of applied compressive and shear stress states differs from the effect of applied tensile stress regarding morphological anisotropy.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2022)
Article
Mathematics, Interdisciplinary Applications
Alexander S. S. Davis, Vinamra Agrawal
Summary: In this research, novel techniques within the concurrent atomistic-continuum (CAC) multiscale framework were developed to simulate shock wave propagation through a two-dimensional, single-crystal lattice. Two moving window methods were incorporated to track the shock front and prevent spurious wave reflections. The simulation results were compared to analytical models and previous data, and the effects of lattice orientation on shock response were discussed. Parametric studies were performed to analyze the structure of the shock front. The efficiency of the model was compared to molecular dynamics simulations, and the potential for more complex studies involving composites and alloys was highlighted.
COMPUTATIONAL MECHANICS
(2023)
Article
Engineering, Multidisciplinary
V. I. Kushch
Summary: The elastic fields, surface constants, and effective elastic moduli of nanoparticles are studied using classical molecular dynamics and continuum mechanics. Two analytical models of isotropic nanoparticles are considered, one simulating the effect of free surface energy and the other taking into account the surface effect based on Gurtin-Murdoch theory. The effective elastic moduli of nanoparticles are evaluated using a surface averaging scheme. The calibrated analytical models correctly predict the size effect of surface free energy on various properties of nanoparticles.
INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE
(2023)
Article
Mechanics
Q. Tan, S. A. Hosseini, A. Seidel-Morgenstern, D. Thevenin, H. Lorenz
Summary: The present study focuses on the development and validation of a modified phase-field model for simulating snowflake crystal growth. The model accurately captures the coupling between species and phase growth, as well as the hydrodynamics-induced asymmetrical growth. The validated model is used to simulate snowflake growth under different ambient conditions, and the resulting crystal habits are compared to experimental data. The study also investigates the effects of forced convection on snowflake growth.
Article
Physics, Fluids & Plasmas
Z. Chen, C. Shu, L. M. Yang, X. Zhao, N. Y. Liu
Summary: This article introduces a simplified phase-field lattice Boltzmann method (PF-SLBM) for modeling solid-liquid phase change problems within a pure material. Through benchmark tests and validations, the accuracy, stability, and boundary treatment of the proposed PF-SLBM are confirmed, and its application to simulations of partially melted or frozen cavities demonstrates its potential in resolving practical problems.
Article
Computer Science, Interdisciplinary Applications
Reza Haghani-Hassan-Abadi, Abbas Fakhari, Mohammad-Hassan Rahimian
Summary: Based on the Allen-Cahn equation, a phase-field model for liquid-vapor phase change phenomena is proposed, which is validated through numerical simulations and comparison with analytical solutions. The model includes phase-change effects, mass transfer, and interface motion, showing good agreement with empirical correlations in practical applications.
JOURNAL OF COMPUTATIONAL PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
S. Karthik, A. Rajagopal, J. N. Reddy
Summary: This work presents a nonlocal phase field model for damage in brittle materials, incorporating a nonconservative order parameter and a new degradation function for damage evolution. The hypothesis of strain equivalence and strain energy equivalence are adopted to predict damage evolution, and a conjugate force to damage is derived. The modified Arc-length method is used to solve the nonlinear system of coupled equations, demonstrating the effectiveness of the proposed damage model through numerical examples.
MECHANICS OF MATERIALS
(2021)
Review
Chemistry, Physical
Ronghai Wu, Yunsong Zhao, Qian Yin, Jiapo Wang, Xing Ai, Zhixun Wen
Summary: Ni-based superalloys are key materials for hot-end components of aeroengines, and studies on their atomistic simulation methods mainly focus on the relationship between micro-defects and mechanical properties.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Materials Science, Multidisciplinary
Shuozhi Xu, Saeed Zare Chavoshi, Yanqing Su
Summary: Multi-principal element alloys (MPEAs) are alloys consisting of three or more principal elements forming solid solution phases. The numerical study of their mechanical properties relies on calculating basic structural parameters like lattice parameter and elastic constants. Direct calculations can be costly, leading to some studies using only one atomic configuration or indirect methods for estimation. Results show that the coefficient of variation using the first approach is positively correlated with lattice distortion in MPEAs.
COMPUTATIONAL MATERIALS SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Yang Bai, Jaber Rezaei Mianroodi, Yan Ma, Alisson Kwiatkowski da Silva, Bob Svendsen, Dierk Raabe
Summary: This study developed a model that explores the interaction between phase transformation, chemical reaction, species diffusion, deformation, and microstructure evolution. The simulations revealed that elastic stress had a negative impact on phase transformations, but high elastic stress could accelerate the transformation and result in a higher reduction degree. The model successfully predicted the observed microstructure evolution in experiments and found that filled pores with water vapor could influence the local reaction atmosphere and dynamics.
Article
Materials Science, Multidisciplinary
E. Scharifi, J. R. Mianroodi, M. Roscher, U. Weidig, E. A. Jaegle, K. Steinhoff
Summary: This study investigates the effect of coupled thermo-mechanical phenomena in the differential cooling technology for press hardening of high strength steel and precipitation-hardening of aluminum alloy AA7075. The aim is to create graded mechanical properties within one part by tailored microstructural distribution. The distribution of detected precipitations after aging is correlated with the measured hardness profile. Different types and morphologies of precipitates are observed at characteristic positions of the part.
Article
Materials Science, Multidisciplinary
Jaber Rezaei Mianroodi, Pratheek Shanthraj, Alisson Kwiatkowski da Silva, Bob Svendsen, Dierk Raabe
Summary: This study investigates the Mn enrichment at dislocations in Fe-Mn alloys through modeling and experimental characterization. Both finite-deformation microscopic phase-field chemomechanics (MPFCM) and Monte Carlo molecular dynamics (MCMD) are used. The results show that both MPFCM and MCMD predict a non-zero hydrostatic stress field in screw cores, and the amount of solute segregating to screw cores is much less than that to edge cores. The concentration dependence of the solute misfit distortion has the strongest effect, and the prediction of Mn concentration along a straight dislocation line by MPFCM differs from the experimental results.
Article
Chemistry, Physical
Hui Zheng, Lauren T. W. Fey, Xiang-Guo Li, Yong-Jie Hu, Liang Qi, Chi Chen, Shuozhi Xu, Irene J. Beyerlein, Shyue Ping Ong
Summary: In this study, the influence of short-range ordering (SRO) on dislocation glide in MoNbTi and TaNbTi RMPEAs is investigated using a multi-scale modeling approach. The results show that MoNbTi exhibits a higher degree of SRO than TaNbTi, and the local composition directly affects the unstable stacking fault energies (USFEs). Increasing SRO leads to higher mean USFEs and stress required for dislocation glide. Gliding dislocations experience significant hardening due to pinning and depinning caused by random compositional fluctuations, with higher SRO decreasing the degree of USFE dispersion and amount of hardening. Lastly, the applied stress is shown to affect the morphology of an expanding dislocation loop.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Chemistry, Physical
Mohammad S. Khorrami, Jaber R. Mianroodi, Nima H. Siboni, Pawan Goyal, Bob Svendsen, Peter Benner, Dierk Raabe
Summary: The purpose of this work is to develop a trained artificial neural network for surrogate modeling of the mechanical response of elasto-viscoplastic grain microstructures. A U-Net-based convolutional neural network (CNN) is trained using numerical solutions for the von Mises stress field from initial-boundary-value problems (IBVPs) for mechanical equilibrium in such microstructures subject to quasi-static uniaxial extension. The resulting trained CNN (tCNN) accurately reproduces the von Mises stress field about 500 times faster than numerical solutions based on spectral methods. The application of the tCNN to test cases not contained in the training dataset is also investigated and discussed.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Xinren Chen, Jaber Rezaei Mianroodi, Chuanlai Liu, Xuyang Zhou, Dirk Ponge, Baptiste Gault, Bob Svendsen, Dierk Raabe
Summary: In aluminum alloys, solute atoms often trap excess vacancies, resulting in a change in the number of mobile vacancies and affecting solute diffusion and precipitate formation. This study investigates vacancy trapping indirectly in the Al-Sn binary alloy and reveals that the addition of Sn reduces the density of quenched-in Frank loops. Modeling of vacancy trapping by solutes during quenching shows the influence of vacancy-solute binding energy, solute concentration, and temperature on the trapping process.
Article
Engineering, Mechanical
Ashley M. Roach, Shuozhi Xu, Darby J. Luscher, Daniel S. Gianola, Irene J. Beyerlein
Summary: In this study, the nanovoid strengthening and the impact of void size, void spacing, and material properties on dislocation bypass mechanisms are investigated. The analysis shows that the critical bypass stress is determined by the linear void fraction, effective isotropic shear modulus, and ratio of intrinsic to unstable stacking fault energies.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Chemistry, Physical
Shuozhi Xu, Abdullah Al Mamun, Sai Mu, Yanqing Su
Summary: Metallic nanowires are widely used as small-scale structural materials due to their small volume and high strength. The mechanical properties of nanowires in pure metals are well understood, but the deformation in metallic alloys is still unclear. In this study, we perform atomistic simulations and find that dislocation slips and twinning control the plastic deformation of nanowires in refractory multi-principal element alloys (RMPEAs). Furthermore, we discover that RMPEAs have reduced tension-compression asymmetry compared to pure metals.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Physical
Xiang-Guo Li, Qian Zhang, Shenghua Liu, Jing Shuai
Summary: The strength of nanocrystalline metal increases as the grain size decreases, following the Hall-Petch relation. However, this relation breaks down when the grains become too small. A study on Ni-Mo alloys demonstrates that the inverse Hall-Petch relation can be successfully reproduced in polycrystals by changing the dominant deformation mechanism. This study provides insights into the complex strengthening mechanisms in nanocrystals and opens up new possibilities for tailoring their mechanical properties.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Weisen Ji, Wu-Rong Jian, Yanqing Su, Shuozhi Xu, Irene J. J. Beyerlein
Summary: Metallic nanolaminates have higher strength than coarse laminates. The strength of these materials is related to the stress required for dislocations to pass through the nanometer-thick layers, known as confined layer slip (CLS). Atomistic simulations of nanolaminated Cu with incoherent interfaces show that the intrinsic stacking fault energy affects the structure of both the dislocation core and the interfaces, and the critical stress for CLS scales positively with the energy of the incoherent interface, but negatively with the ratio between the intrinsic and unstable stacking fault energies.
JOURNAL OF MATERIALS SCIENCE
(2023)
Article
Crystallography
Yipeng Peng, Rigelesaiyin Ji, Thanh Phan, Xiang Chen, Ning Zhang, Shuozhi Xu, Ashraf Bastawros, Liming Xiong
Summary: In this paper, concurrent atomistic-continuum simulations were used to investigate hydrogen diffusion along a grain boundary in a plastically deformed bcc iron sample. It was found that the accumulation of dislocations near the hydrogen-charged grain boundary can induce a high local internal stress and affect the diffusion rate. These findings can provide insights into the interplay between plasticity, hydrogen diffusion, and crack initiation.
Article
Computer Science, Interdisciplinary Applications
Dierk Raabe, Jaber Rezaei Mianroodi, Joerg Neugebauer
Summary: The chemical space for designing materials is practically infinite, making progress by traditional physics-based modeling challenging. However, there is a lack of training data for artificial intelligence to identify composition-structure-property relations. This Perspective explores the potential of combining physics laws with AI to discover new chemically complex materials.
NATURE COMPUTATIONAL SCIENCE
(2023)