Deformation and strain concentrations in coarse-grained alpha-uranium
<p>This thesis presents an experimental characterisation of the deformation of coarse-grained cast alpha-uranium to assist the development of crystal plasticity finite element (CPFE) models. </p> <p>Uranium exhibits elastic and plastic anisotropy and deforms heterogeneously via mu...
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| 格式: | Thesis |
| 語言: | English |
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2019
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| 總結: | <p>This thesis presents an experimental characterisation of the deformation of coarse-grained cast alpha-uranium to assist the development of crystal plasticity finite element (CPFE) models. </p>
<p>Uranium exhibits elastic and plastic anisotropy and deforms heterogeneously via multiple slip and twinning modes. Strain concentrations that develop in the deforming grains may initiate fracture. There is an industrially-motivated drive to perform CPFE simulations that incorporate the unique properties of uranium to allow a better understanding of the conditions leading to fracture.
Experiments have been performed by the author to provide data for calibration and validation of a CPFE model for cast α-uranium. </p>
<p>Time-of flight neutron diffraction was used to measure internal lattice strain development and texture changes during in-situ tension and compression. The coarse microstructure raises experimental challenges these are solved in a subsequent experiment. Deformation twinning causes a lattice reorientation that is detectable as a macroscopic texture change. A novel analysis was performed allowing active twinning modes to be identified from the texture changes. Twinning accounts for the observed tension-compression asymmetry in the material. </p>
<p>Digital image correlation (DIC) was used to measure the full-field surface strains during tensile deformation of cast uranium. The measured strains were highly heterogeneous the locations of strain concentrations were related to the crystallographic orientations measured with electron backscatter diffraction (EBSD). </p>
<p>The data generated in this thesis are found to be suitable to calibrate and validate a crystal plasticity model of cast α-uranium.</p> |
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