skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Physics-assisted data-driven stochastic reduced-order models for attribution of heterogeneous stress distributions in low-grain polycrystals
Title: Physics-assisted data-driven stochastic reduced-order models for attribution of heterogeneous stress distributions in low-grain polycrystals
Understanding stress distributions at grain boundaries in polycrystalline materials is crucial for predicting damaged nucleation sites. In high-purity materials, voids often nucleate at grain boundaries due to high stress from granular interactions and weakened atomic ordering. While traditional crystal plasticity models simulate grain-level mechanics, their high computational cost often prevents systematic identification of critical microstructural features and efficient forecast of extreme damage events. This paper addresses these challenges by developing a computationally efficient physics-assisted statistical modelling framework. The method starts by leveraging physical knowledge to hypothesize a broad set of microstructural factors influencing stress conditions. Causal inference is then applied to reveal the predominant features with physical explanations, leading to a parsimonious statistical model. A conditional Gaussian mixture model (CGMM) is employed when the identified relationship is utilized as a predictive model to quantify the uncertainty not readily explained by these features. Using body-centred cubic (BCC) tantalum as a representative material, a series of synthetic microstructures from single- to octu-crystal configurations are created. Results show that high-stress states strongly correlate with the elastic and plastic deformation capabilities and the directional misalignment of grain responses near boundaries. The statistical model achieves rapid and accurate forecasts, demonstrating its potential for analysing realistic polycrystalline materials.  more » « less
Award ID(s):
2118399
PAR ID:
10659662
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
Royal Society
Date Published:
Journal Name:
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
Volume:
481
Issue:
2309
ISSN:
1364-5021
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; ; ; (, Nature Communications)
    Abstract During cyclic loading, localization of intragranular deformation due to crystallographic slip acts as a precursor for crack initiation, often at coherent twin boundaries. A suite of high-resolution synchrotron X-ray characterizations, coupled with a crystal plasticity simulation, was conducted on a polycrystalline nickel-based superalloy microstructure near a parent-twin boundary in order to understand the deformation localization behavior of this critical, 3D microstructural configuration. Dark-field X-ray microscopy was spatially linked to high energy X-ray diffraction microscopy and X-ray diffraction contrast tomography in order to quantify, with cutting-edge resolution, an intragranular misorientation and high elastic strain gradients near a twin boundary. These observations quantify the extreme sub-grain scale stress gradients present in polycrystalline microstructures, which often lead to fatigue failure. 
    more » « less
  2. ; ; ; ; ; ; (, Advanced Functional Materials)
    Abstract Grain boundaries critically limit the electronic performance of oxide perovskites. These interfaces lower the carrier mobilities of polycrystalline materials by several orders of magnitude compared to single crystals. Despite extensive effort, improving the mobility of polycrystalline materials (to meet the performance of single crystals) is still a severe challenge. In this work, the grain boundary effect is eliminated in perovskite strontium titanate (STO) by incorporating graphene into the polycrystalline microstructure. An effective mass model provides strong evidence that polycrystalline graphene/strontium titanate (G/STO) nanocomposites approach single crystal‐like charge transport. This phenomenological model reduces the complexity of analyzing charge transport properties so that a quantitative comparison can be made between the nanocomposites and STO single crystals. In other related works, graphene composites also optimize the thermal transport properties of thermoelectric materials. Therefore, decorating grain boundaries with graphene appears to be a robust strategy to achieve “phonon glass–electron crystal” behavior in oxide perovskites. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; (, npj Computational Materials)
    Abstract Although multiple oxide-based solid electrolyte materials with intrinsically high ionic conductivities have emerged, practical processing and synthesis routes introduce grain boundaries and other interfaces that can perturb primary conduction channels. To directly probe these effects, we demonstrate an efficient and general mesoscopic computational method capable of predicting effective ionic conductivity through a complex polycrystalline oxide-based solid electrolyte microstructure without relying on simplified equivalent circuit description. We parameterize the framework for Li7-xLa3Zr2O12(LLZO) garnet solid electrolyte by combining synthetic microstructures from phase-field simulations with diffusivities from molecular dynamics simulations of ordered and disordered systems. Systematically designed simulations reveal an interdependence between atomistic and mesoscopic microstructural impacts on the effective ionic conductivity of polycrystalline LLZO, quantified by newly defined metrics that characterize the complex ionic transport mechanism. Our results provide fundamental understanding of the physical origins of the reported variability in ionic conductivities based on an extensive analysis of literature data, while simultaneously outlining practical design guidance for achieving desired ionic transport properties based on conditions for which sensitivity to microstructural features is highest. Additional implications of our results are discussed, including a possible connection between ion conduction behavior and dendrite formation. 
    more » « less
  4. ; ; ; ; ; (, Fatigue & Fracture of Engineering Materials & Structures)
    Abstract Microstructurally small fatigue‐crack growth in polycrystalline materials is highly three‐dimensional due to sensitivity to local microstructural features (e.g., grains). One requirement for modeling microstructurally sensitive crack propagation is establishing the criteria that govern crack evolution, including crack deflection. Here, a high‐fidelity finite‐element modeling framework is used to assess the performance and validity of various crack‐growth criteria, including slip‐based metrics (e.g., fatigue‐indicator parameters), as potential criteria for predicting three‐dimensional crack paths in polycrystalline materials. The modeling framework represents cracks as geometrically explicit discontinuities and involves voxel‐based remeshing, mesh‐gradation control, and a crystal‐plasticity constitutive model. The predictions are compared to experimental measurements of WE43 magnesium samples subject to fatigue loading, for which three‐dimensional grain structures and fatigue‐crack surfaces were measured post‐mortem using near‐field high‐energy x‐ray diffraction microscopy and x‐ray computed tomography. Findings from this work are expected to improve the predictive capabilities of simulations involving microstructurally small fatigue‐crack growth in polycrystalline materials. 
    more » « less
  5. ; (, Science Advances)
    The complexity of shear-induced grain boundary dynamics has been historically difficult to view at the atomic scale. Meanwhile, two-dimensional (2D) colloidal crystals have gained prominence as model systems to easily explore grain boundary dynamics at single-particle resolution but have fallen short at exploring these dynamics under shear. Here, we demonstrate how an inherent interfacial shear in 2D colloidal crystals drives microstructural evolution. By assembling paramagnetic particles into polycrystalline sheets using a rotating magnetic field, we generate a particle circulation at the interface of particle-free voids. This circulation shears the crystalline bulk, operating as both a source and sink for grain boundaries. Furthermore, we show that the Read-Shockley theory for hard-condensed matter predicts the misorientation angle and energy of shear-induced low-angle grain boundaries based on their regular defect spacing. Model systems containing shear provide an ideal platform to elucidate shear-induced grain boundary dynamics for use in engineering improved/advanced materials. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email