Thermal damage modelling of the microstructure of model refractory materials by the discrete element method
PLEDEL Q. 1, HUGER M. 1, ANDRÉ D. 1
1 University of Limoges, Institute of Research for Ceramics (IRCER), UMR 7315, European Ceramics Center, Limoges, France
Refractories are ceramic materials resistant to very high temperatures. Used in environments with harsh solicitations, a better understanding between the macroscopic physical properties and the micro-structural aspects is necessary to optimize their use. This work proposes to focus on the resistance to thermal shocks by micro-mechanical modelling.
To do this, numerical simulations are performed to model the microcracking caused by the thermal expansion mismatch between the constituents and its influence on the non-linear stress-strain behavior of such materials. The work has been performed with GranOO, a software using the discrete element method (DEM), to which is added a periodic homogenization method to consider the phenomena at microscopic scale on the macroscopic properties. The damage process is studied during the cooling of refractories materials in order to reproduce a multi-cracked state and to understand the mechanisms depending on parameters such as the proportion of the constituents, their thermal expansion anisotropies and the geometry of the model. From these simulations, the main macroscopic mechanical properties involved in the resistance to thermal shocks can be analyzed and related to the microcracking state of the system. These results are then compared with analytical models and experimental results. These developments allow a better understanding between microstructure and macroscopic behavior. This work envisages the potential of the discrete element method to predict the thermomechanical behavior of microcracked media.