Micro-cantilever beam experiments and modeling in porous polycrystalline UO2

Bowen Gong, David Frazer, Benjamin Shaffer, Harn Chyi Lim, Peter Hosemann, Pedro Peralta

Research output: Contribution to journalArticlepeer-review

Abstract

Understanding the impact of microstructure on the thermo-mechanical behavior of oxide nuclear fuels is vital to predicting their performance through multiscale models. Evaluating the mechanical properties at the sub-grain length scale is key to developing these multiscale models. In this work, 3D finite element (FE) models were constructed to simulate the micrometer-scale bending of micro-cantilever beams fabricated using porous polycrystalline uranium dioxide (UO2) and tested at room temperature. The results showed that the porosity and elastic anisotropy of individual grains can play a significant role in determining the effective mechanical properties of the material deduced from the tests. Specifically, the porosity had a non-negligible effect, given that the pore size was of the same order of magnitude as the dimensions of the micro-beams. Correlations between load-deflection data, pore location, and elastic properties (effective Young's modulus) were investigated using UO2 micro-beam FE models, where pore clusters were included and placed at different locations along the length of the beam. Results indicated that the presence of pore clusters near the substrate, i.e., the clamp of the micro-cantilever beam, has the strongest effect on the load-deflection behavior, with the porosity leading to a reduction of stiffness that is the largest for any location of the pore clusters. Furthermore, it was also found that pore clusters located towards the middle of the span and close to the end of the beam have a comparatively small effect on the load-deflection behavior. Therefore, it is concluded that accurate estimates of Young's modulus can be obtained from micro-cantilever experiments after accounting for porosity on the one third of the beam length close to the clamp. This, in turn, provides an avenue to improve microscale experiments and their analysis in porous, anisotropic elastic materials.

Original languageEnglish (US)
Article number153210
JournalJournal of Nuclear Materials
Volume557
DOIs
StatePublished - Dec 15 2021
Externally publishedYes

Keywords

  • Effect of porosity
  • Finite element modeling
  • Microscale mechanical testing
  • Oxide nuclear fuel

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Materials Science(all)
  • Nuclear Energy and Engineering

Fingerprint

Dive into the research topics of 'Micro-cantilever beam experiments and modeling in porous polycrystalline UO<sub>2</sub>'. Together they form a unique fingerprint.

Cite this