On the state of deformation in a polycrystalline material in three-dimension: Elastic strains, lattice rotations, and deformation mechanisms

Abdolvand, Hamidreza; Wright, Jonathan P.; Wilkinson, Angus J.

doi:10.1016/j.ijplas.2018.03.006

Cited by 25 publications

(9 citation statements)

References 54 publications

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“…Crystal plasticity fast Fourier transform (CP-FFT). To conduct the CP-FFT simulations, a volume element has first been extracted from the measured 3D grain map of the Mg-1 specimen obtained at Preload 46 . To reconstruct the volume element, a weighted Voronoï tessellation has been performed with 400 seeds, corresponding to grains located in the centre of the probed volume.…”

Section: Discussionmentioning

confidence: 99%

Formation and annihilation of stressed deformation twins in magnesium

et al. 2021

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The mechanical response of polycrystalline materials to an externally applied load and their in-service performance depend on the local load partitioning among the constituent crystals. In hexagonal close-packed polycrystals such load partitioning is significantly affected by deformation twinning. Here we report in-situ compression-tension experiments conducted on magnesium specimens to measure the evolution of grain resolved tensorial stresses and formation and annihilation of twins. More than 13000 grains and 1300 twin-parent pairs are studied individually using three-dimensional synchrotron X-ray diffraction. It is shown that at the early stages of plasticity, the axial stress in twins is higher than that of parents, yet twins relax with further loading. While a sign reversal is observed for the resolved shear stress (RSS) acting on the twin habit plane in the parent, the sign of RSS within the majority of twins stays unchanged until twin annihilation during the load reversal. The variations of measured average stresses across parents and twins are also investigated.

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Section: Discussionmentioning

confidence: 99%

Formation and annihilation of stressed deformation twins in magnesium

et al. 2021

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“…The EBSD-based CPFE model was assigned the strain gradient constitutive formulation to simulate the LCF behavior of both original fine grain (d ¼ 27 mm) and the coarse grain (d ¼ 209 mm) CoCr alloys, using the modified constitutive law specified in equation (17). Two fatigue tests were carried out on this annealed alloy at the strain ranges of AE0.5% and AE 1.0%.…”

Section: Gnd-induced Strain Gradient Length-scale Size Effectmentioning

confidence: 99%

“…Numerous artificial methods have been adopted for generating idealised polycrystalline representative volume element (RVE) models, such as homogenised regular shape microstructures 14,15 , Voronoi tessellation (VT) based 2D maps consisting of irregular grain morphologies defined by straight grain boundaries 16 and the 3D polycrystalline aggregate cube 17,18 methods. These methods have some important limitations:…”

Section: Introductionmentioning

confidence: 99%

“…12 In parallel, advances in computational modeling methodologies, including crystal-plasticity finite element (CPFE) modeling, have permitted advanced microstructural mechanical characterization. 13 Numerous artificial methods have been adopted for generating idealized polycrystalline representative volume element (RVE) models, such as homogenized regular shape microstructures, 14,15 Voronoi tessellation (VT)-based 2D maps consisting of irregular grain morphologies defined by straight grain boundaries, 16 and the 3D polycrystalline aggregate cube 17,18 methods. These methods have some important limitations:…”

Section: Introductionmentioning

confidence: 99%

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A high-fidelity crystal-plasticity finite element methodology for low-cycle fatigue using automatic electron backscatter diffraction scan conversion: Application to hot-rolled cobalt–chromium alloy

Leen

Harrison

2021

Proceedings of the Institution of Mechanical Engineers, Part L:

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The common approach to crystal-plasticity finite element modeling for load-bearing prediction of metallic structures involves the simulation of simplified grain morphology and substructure detail. This paper details a methodology for predicting the structure–property effect of as-manufactured microstructure, including true grain morphology and orientation, on cyclic plasticity, and fatigue crack initiation in biomedical-grade CoCr alloy. The methodology generates high-fidelity crystal-plasticity finite element models, by directly converting measured electron backscatter diffraction metal microstructure grain maps into finite element microstructural models, and thus captures essential grain definition for improved microstructure–property analyses. This electron backscatter diffraction-based method for crystal-plasticity finite element model generation is shown to give approximately 10% improved agreement for fatigue life prediction, compared with the more commonly used Voronoi tessellation method. However, the added microstructural detail available in electron backscatter diffraction–crystal-plasticity finite element did not significantly alter the bulk stress–strain response prediction, compared to Voronoi tessellation–crystal-plasticity finite element. The new electron backscatter diffraction-based method within a strain-gradient crystal-plasticity finite element model is also applied to predict measured grain size effects for cyclic plasticity and fatigue crack initiation, and shows the concentration of geometrically necessary dislocations around true grain boundaries, with smaller grain samples exhibiting higher overall geometrically necessary dislocations concentrations. In addition, minimum model sizes for Voronoi tessellation–crystal-plasticity finite element and electron backscatter diffraction–crystal-plasticity finite element models are proposed for cyclic hysteresis and fatigue crack initiation prediction.

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“…If lattice strains have long been measured (and still are) in whole grain families using X-ray diffraction [24], the pursuit of local strains have seen a number of recent developments. The first level of refinement comes from 3DXRD or far-field HEDM that allow to retrieve the average elastic strain tensor of each grain during 4D experiments [25,26]. The second level is to reach truly intragranular strain.…”

Section: Introductionmentioning

confidence: 99%

In situ 4D mechanical testing of structural materials: The data challenge

Proudhon

Pelerin

King

et al. 2020

Current Opinion in Solid State and Materials Science

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This papers presents recent progress with materials investigations via in situ mechanical testing at the synchrotron, so called 4D experiments. More automated and more integrated stress rigs now allow to produce new kind of data sets to study deformation and fracture of structural materials. Two recent examples are presented, one with a polymer material and another one with a polycrystalline metallic alloy. Challenges with data organisation and storage and automatic analysis are discussed in the view of the upgrade of the main synchrotron sources which will greatly increase the number and size of the future data sets.

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On the state of deformation in a polycrystalline material in three-dimension: Elastic strains, lattice rotations, and deformation mechanisms

Cited by 25 publications

References 54 publications

Formation and annihilation of stressed deformation twins in magnesium

Formation and annihilation of stressed deformation twins in magnesium

A high-fidelity crystal-plasticity finite element methodology for low-cycle fatigue using automatic electron backscatter diffraction scan conversion: Application to hot-rolled cobalt–chromium alloy

In situ 4D mechanical testing of structural materials: The data challenge

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