Micromechanical modeling of single crystal and polycrystalline UO2 at elevated temperatures

Modelling of UO2 mechanical behavior requires detailed knowledge of the local stresses and strains dur-ing the fuel's operation in normal and accident conditions. Therefore, a crystal plasticity formulation is proposed for polycrystalline UO2. The model contains a dislocation-density-based formulation including three slip families and their interactions. The model is parametrized with single crystal and polycrystal experimental data using an optimization scheme. The model's capability to represent yield point, strain hardening behavior, temperature and strain rate dependencies are evaluated. Finally, different approaches to include porosity at the polycrystal are analyzed to assess the effect of porosity on homogenized macro-scopic stress-strain behavior, and stress/strain localization at the grain level.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

Automated summary

A crystal plasticity model is proposed for modelling the mechanical behavior of polycrystalline UO2. The model includes a dislocation-density-based formulation with three slip families and their interactions. It is parametrized using single crystal and polycrystal experimental data and evaluated for yield point, strain hardening behavior, temperature and strain rate dependencies. The effect of porosity on homogenized macroscopic stress-strain behavior and stress/strain localization at the grain level is analyzed.