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Persistent URL http://purl.org/net/epubs/work/54204
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Record Id 54204
Title Feasibility study of neutron strain tomography
Abstract In many respects, strain mapping by neutron and X-ray diffraction can be regarded as imaging techniques in 2D or 3D, i.e. the spatially resolved determination of a material property within the interior of an object. However, whereas in the conventional sense 3D imaging is normally concerned with the spatial variation of attenuation coefficient, in the case of strain mapping it is the spatial variation of elastic strain which is being 'imaged'. The situation is further complicated by the fact that the property being imaged (the strain tensor) is itself multi-component and directionally dependent. Characterising the 3D strain distribution at any particular point requires the measurement of six independent components which make up the second order strain tensor. Mapping the complete strain distribution throughout large volumes thus presents significant practical challenges. The solution proposed here, based on the Bragg edge neutron transmission method, is non-destructive, and in principle allows a three-dimensional reconstruction of the residual strain throughout the bulk of the sample. The principle of this novel approach is to analyze residual strain fields by de-convolution of unknown distributions of residual elastic strains from a data set collected over a range of positions and rotations, allowing the possibility of reconstructing the entire strain distribution within the interior of an object. The idea is that the strain tensor, which has multiple degrees of freedom, may be reconstructed from a redundant set of lower order projection data. This method is the inversion of a two-dimensional data set in order to obtain three-dimensional information, analogous to the familiar tomographic methods used to reconstruct three-dimensional density distributions in conventional imaging. Case studies will be discussed to illustrates the application of the principle using neutron transmission Bragg edge measurements. The methods described here can readily be applied to high-energy X-ray diffraction measurements.
Organisation ISIS , ISIS-ENGIN-X , STFC
Keywords tomography , residaul stress analysis , neutron time-of-flight , Engineering
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Language English (EN)
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Presentation Presented at 12th European Powder Diffraction Conference, Darmstadt, Germany, 27-30 Aug 2010. 2010
Journal Article Mesomechanics 1 (2009): 185. 2009