Date of Award:

12-2021

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Mechanical and Aerospace Engineering

Committee Chair(s)

Ryan Berke

Committee

Ryan Berke

Committee

Tadd Truscott

Committee

Ling Liu

Committee

Hailei Wang

Committee

Nicholas Roberts

Abstract

Nuclear fuel cladding in light water reactors, often made of zirconium alloys, is naturally made more brittle by exposure to the water coolant during normal reactor operation. However, this embrittlement by zirconium hydrides changes the mechanical behavior of the cladding material, affecting how it will deform and what may cause it to fail. Because the cladding already has different properties in different material directions, mechanical testing also needs to be direction specific. In addition, to understand the effects that these microscale hydride features have, measurements of deforming cladding need to be at a microscale. This dissertation describes several high-magnification innovations and advancements in digital image correlation (DIC), a non-contact method for measuring displacement and strain of test specimens during experiments. First, a high-magnification UV lens is demonstrated to be capable of DIC measurements with improved spatial resolution and at high temperatures. Second, previously developed super resolution imaging techniques are applied to DIC measurements of directional ring test specimens, again improving resolution and measurement quality. Third, image capture settings are optimized to balance a tradeoff between poor depth of field and the diffraction of light, both of which cause blurred images and poorer DIC measurements. Fourth, several test arrangements are analyzed with computer modelling to determine the best method for directional tests of the cladding. Finally, the techniques are used to perform high-magnification tension tests for hydrided ring cladding specimens.

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