Tomographic Reconstruction of Two-Dimensional Residual Strain Fields from Bragg-Edge Neutron Imaging

Gregg, Alexander; Hendriks, Johannes N.; Wensrich, C.M.; Wills, Adrian; Tremsin, Anton S.; Luzin, Vladimir; Shinohara, T.; Kirstein, O.; Meylan, Michael H.; Kisi, Erich H.

doi:10.1103/physrevapplied.10.064034

Cited by 21 publications

(51 citation statements)

References 28 publications

(45 reference statements)

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“…Although many options exist for the choice of covariance function

K_{φ} false(boldx, x^{'} false)

, the squared exponential and Matern covariance functions were both shown to be suitable . It is also possible to build a covariance function from the finite two‐dimensional Fourier basis used; however, we would then be required to specify the number of basis functions used, limiting the expressiveness of the Gaussian process.…”

Section: Reconstruction Algorithmmentioning

confidence: 99%

“…Reconstructing the strain field of the classical cantilevered beam has been examined . As such, we use this example to demonstrate the improvement that incorporating boundary tractions has on the reconstruction.…”

Section: Simulationmentioning

confidence: 99%

“…A well‐known example is computed tomography (CT) where a set of flat two‐dimensional X‐ray images are analysed to build a three‐dimensional image of the scalar density. In the area of experimental mechanics, new techniques for high resolution imaging of strain have created significant interest in associated tomographic reconstruction processes . In contrast to conventional CT, tomographic reconstruction of strain seeks to determine the rank‐2 tensor strain field from a set of scalar two‐dimensional projections of the strain field.…”

Section: Introductionmentioning

confidence: 99%

“…Conceptually, both Gregg et al and Jidling et al reconstruct the strain field by fitting functions. The differences lie in how this is achieved; a GP based method has the potential for greater expressiveness as it is not limited to a finite set of basis functions.…”

Section: Introductionmentioning

confidence: 99%

“…Further, we provide an alternate solution to the problem of numerical integration which avoids the need for the approximation method. A convergence comparison of the methods given and the extended method is presented for the reconstruction of the Saint‐Venant approximate cantilevered beam strain field, and finally, a comparison of applying the methods and the extended method to reconstruct a residual strain field from experimental data is provided.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Implementation of traction constraints in Bragg‐edge neutron transmission strain tomography

Hendriks

Gregg

Wensrich

et al. 2019

Strain

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Several recent methods for tomographic reconstruction of stress and strain fields from Bragg-edge neutron strain images have been proposed in the literature. This paper presents an extension of a previously demonstrated approach based on Gaussian process regression that enforces equilibrium in the method. This extension incorporates knowledge of boundary conditions, primarily boundary tractions, into the reconstruction process. This is shown to increase the rate of convergence and is more tolerant of systematic errors that may be present in experimental measurements. An exact expression for a central calculation in this method is also provided which avoids the need for the approximation scheme that was previously used. Convergence of this method for simulated data is compared to existing approaches and a reconstruction from experimental data is provided. Validation of the results to conventional constant wavelength strain measurements and comparison to prior methods show a significant improvement. KEYWORDSBragg-edge neutron imaging, Gaussian process regression, residual stress, strain tomography Strain. 2019;55:e12325.wileyonlinelibrary.com/journal/str

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“…Although many options exist for the choice of covariance function

K_{φ} false(boldx, x^{'} false)

Section: Reconstruction Algorithmmentioning

confidence: 99%

Section: Simulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Implementation of traction constraints in Bragg‐edge neutron transmission strain tomography

Hendriks

Gregg

Wensrich

et al. 2019

Strain

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Voxel‐Based Full‐Field Eigenstrain Reconstruction of Residual Stresses

Uzun

Korsunsky

2023

Adv Eng Mater

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Inverse eigenstrain (inherent strain) analysis methods are shown to be effective for the reconstruction of residual stresses in plane eigenstrain problems (continuously processed bodies) while conversely residual stress reconstruction in discontinuously processed bodies is extremely challenging and necessitates the use of complex regularizing assumptions. Herein, a new generic inverse eigenstrain method suitable for the reconstruction of residual stresses along with residual elastic strains and displacements in discontinuously processed bodies is introduced. The proposed method uses the superposition of eigenstrain radial basis functions together with a set of limited experimental data for model‐free (unconstrained) determination of unknown eigenstrain fields. This approach eliminates the limitations introduced by global basis functions such as polynomials. The novel point of this method is the ability to account for all six components of strain in an isotropic body without using regularizing assumptions. By lifting complex guiding formulation, the fidelity of full‐field eigenstrain reconstruction becomes directly related to the quality of experimental data and proper discretisation of the model domain. The FEniCS implementation has been validated using the experimental data of pointwise high‐energy synchrotron X‐ray diffraction measurements from a bent titanium alloy bar. A hybrid high throughput computing approach is also introduced for effective parallel computing.

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Strain Engineering: A Boosting Strategy for Photocatalysis

et al. 2022

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diffraction (XRD). [6] Computationally, continuum mechanics, [7] molecular dynamics simulations, [8] and density functional theory (DFT) [9] are powerful techniques to simulate the strain conditions. The inelastic strain is generally associated with dislocation plasticity or fracture. The dislocation plasticity should be avoided in elastic strain studies since the lattice dislocation can release the elastic strain besides disturbing the original electronic structure of materials. [10] Hence, the strain in this review is limited to elastic strain unless by a particular statement. The strain effect is based on the difference in reactivity according to the atomic arrangement (involving compressed or expanded arrangements) of surface atoms. [1a] The long-range strain effect (usually includes 1-6 monolayers) differs from the ligand effect and ensemble effect (both dominate at 1-2 monolayers), impacting the surface reactivities in more than a few atomic layers. [1a,11] With the development of nanotechnologies and characterization techniques, strain effect on materials can be well engineered, tuned, and controlled toward various applications (denoted as strain engineering), such as photo-/electrocatalysis, [12] superconductivity, [13] and semiconductor devices. [14] Photocatalysis, one of the most important and promising forms of catalysis, has attracted widespread attention as an appealing and promising solution to alleviate global energy and environmental issues, while its practical application primarily remains hampered by the low η abs , η cs , and η cs (η abs : light absorption efficiency, η cs : carrier separation efficiency, η cat : catalytic efficiency). [15] These three fundamental processes govern the overall photocatalytic performance (η = η abs × η cs × η cat ). [16] A variety of modification strategies are proposed to improve the photocatalytic properties of materials (e.g., strain engineering, interface engineering, crystal facet engineering, and surface modification). [17] Amongst these modification strategies that have been investigated to date, strain engineering is allowed to precisely tune the band structure [10b,18] and carrier mobility of semiconductor photocatalysts, [19] and the adsorption energy of reaction substrates or intermediates, [9,12i,20] so it has great potential to break the bottleneck of photocatalysis. While some progress has been made regarding strained photo catalysis, many difficulties and challenges still need to be overcome, including tunable creation and measurement of strain, strained photocatalysis principles, and its further applications in various photocatalytic reactions. [20,21] In addition, strain engineering in nanomaterials applied for electrocatalysis and solar cells is likely to provide novel insights for developing high-performance Whilst the photocatalytic technique is considered to be one of the most significant routes to address the energy crisis and global environmental challenges, the solar-to-chemical conversion efficiency is still far from satisfying prac...

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Tomographic Reconstruction of Two-Dimensional Residual Strain Fields from Bragg-Edge Neutron Imaging

Cited by 21 publications

References 28 publications

Implementation of traction constraints in Bragg‐edge neutron transmission strain tomography

Implementation of traction constraints in Bragg‐edge neutron transmission strain tomography

Voxel‐Based Full‐Field Eigenstrain Reconstruction of Residual Stresses

Strain Engineering: A Boosting Strategy for Photocatalysis

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