Bragg-edge neutron transmission strain tomography for in situ loadings

Wensrich, C.M.; Hendriks, Johannes N.; Gregg, Alexander; Meylan, Michael H.; Luzin, Vladimir; Tremsin, Anton S.

doi:10.1016/j.nimb.2016.06.012

Cited by 35 publications

(51 citation statements)

References 12 publications

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“…We first demonstrate this algorithm on the classical cantilevered beam as examined previously by Wensrich et al [11] and shown in Figure 2. Under a plane-stress assumption, the Saint-Venant approximation to the resulting strain field is [16]:…”

Section: Demonstration -Simulationmentioning

confidence: 99%

“…The measured strain is the normal component in the transmission direction of the neutron beam. The success of this approach and development of instruments and associated detector technologies has prompted activity focused on solving the associated tomographic reconstruction problem [6][7][8][9][10][11][12][13]. The aim is to provide a method analogous to conventional Computed Tomography by which the full triaxial strain distribution within a sample could be reconstructed from a sufficient set of Bragg-edge strain images.…”

Section: Introductionmentioning

confidence: 99%

“…DEMONSTRATION -EXPERIMENTALFollowing success in simulation, the algorithm was demonstrated on real-world examples in an experiment on the RADEN energy resolved neutron imaging instrument at the Japan Proton Accelerator Research Complex (J-PARC)[17,18]. This experiment focused on re-Convergence of the algorithm for the cantilevered beam as compared to the boundary reconstruction method presented in Wensrich et al[11].…”

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confidence: 99%

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

et al. 2018

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Bragg-edge strain imaging from energy-resolved neutron transmission measurements poses an interesting tomography problem. The solution to this problem will allow the reconstruction of detailed triaxial stress and strain distributions within polycrystalline solids from sets of Bragg-edge strain images. Work over the last decade has provided some solutions for a limited number of special cases. In this paper, we provide a general approach to reconstruction of an arbitrary system based on a least squares process constrained by equilibrium. This approach is developed in twodimensions before being demonstrated experimentally on two samples using the RADEN instrument at the J-PARC spallation neutron source in Japan. Validation of the resulting reconstructions is provided through a comparison to conventional constant wavelength strain measurements carried out on the KOWARI engineering diffractometer within ANSTO in Australia. The paper concludes with a discussion on the range of problems to be addressed in a three-dimensional implementation.

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Section: Demonstration -Simulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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

et al. 2018

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“…This approach was Figure 2: Neutron spectra from [22] showing the 110 edge on a magnified scale. The wavelength is given in Angstrom = 10 −10 m. Note that the 211 edge is closer to the ideal behaviour of a step in an otherwise linear trend Figure 3: Shifted Bragg edges produce a saw tooth effect but the derivative is a histogram up to an added constant taken for axisymmetric objects by Gregg et al [13], in the general case for synthetic data by Wensrich et al [27], and experimentally for a general case by Henriks et al [14].…”

Section: Neutron Bragg Edge Strain Tomographymentioning

confidence: 78%

Histogram tomography

Lionheart

2020

Mathematics in Engineering

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In many tomographic imaging problems the data consist of integrals along lines or curves. Increasingly we encounter "rich tomography" problems where the quantity imaged is higher dimensional than a scalar per voxel, including vectors tensors and functions. The data can also be higher dimensional and in many cases consists of a one or two dimensional spectrum for each ray. In many such cases the data contain not just integrals along rays but the distribution of values along the ray. If this is discretized into bins we can think of this as a histogram. In this paper we introduce the concept of "histogram tomography". For scalar problems with histogram data this holds the possibility of reconstruction with fewer rays. In vector and tensor problems it holds the promise of reconstruction of images that are in the null space of related integral transforms. For scalar histogram tomography problems we show how bins in the histogram correspond to reconstructing level sets of function, while moments of the distribution are the x-ray transform of powers of the unknown function. In the vector case we give a reconstruction procedure for potential components of the field. We demonstrate how the histogram longitudinal ray transform data can be extracted from Bragg edge neutron spectral data and hence, using moments, a non-linear system of partial differential equations derived for the strain tensor. In x-ray diffraction tomography of strain the transverse ray transform can be deduced from the diffraction pattern the full histogram transverse ray transform cannot. We give an explicit example of distributions of strain along a line that produce the same diffraction pattern, and characterize the null space of the relevant transform.

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“…The algorithm in [24] requires detailed knowledge of the sample position, center of rotation, and orientation. These were determined by matching the known sample geometry to edge height profile over all projections.…”

Section: Experimental Set-upmentioning

confidence: 99%

Bragg-edge elastic strain tomography forin situsystems from energy-resolved neutron transmission imaging

Hendriks

Gregg

Wensrich

et al. 2017

Phys. Rev. Materials

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Technological developments in high resolution time-of-flight neutron detectors have raised the prospect of tomographic reconstruction of elastic strain fields from Bragg-edge strain images. This approach holds the potential to provide a unique window into the full triaxial stress field within solid samples. While general tomographic reconstruction from these images has been shown to be ill-posed, an injective link between measurements and boundary deformations exists for systems subject to in situ applied loads in the absence of residual stress. Recent work has provided an algorithm to achieve tomographic reconstruction for this class of mechanical system. This letter details an experimental proof-of-concept for this algorithm involving the full reconstruction of a biaxial strain field within a non-trivial steel sample. This work was carried out on the RADEN energy resolved neutron imaging instrument within the Japan Proton Accelerator Research Complex, with validation through Digital Image Correlation and constant wavelength neutron strain scans.

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Bragg-edge neutron transmission strain tomography for in situ loadings

Cited by 35 publications

References 12 publications

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

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

Histogram tomography

Bragg-edge elastic strain tomography forin situsystems from energy-resolved neutron transmission imaging

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