Application of discrete element modelling to investigate microstructural effects of anisotropic thermal expansion in polycrystalline ceramics at high temperatures

Refractory ceramics, used in high-temperature industries, have heterogeneous microstructures with multiphase compositions and diverse bonding systems that enable resistance to corrosion, thermal gradients, and shock. Their ability to withstand repeated thermal shocks depends on managing stresses from mismatched Coefficients of Thermal Expansion (CTE), which can initiate microcracks when exceeding tensile strength. Controlled microcracking can, however, enhance fracture energy and toughness, making fracture energy a key indicator of thermal shock resistance. Modelling such complex behaviour remains challenging, driving interest in simulating cracking phenomena like microcracking, branching, and fragmentation. An improved Distinct Lattice Spring Model (iDLSM) incorporating anisotropic thermal expansion, thermomechanical coupling, and crack closure mechanisms effectively reproduces experimental trends in thermal expansion and Young’s modulus, demonstrating strong predictive capability. The enhanced model is further applied to explore micromechanics, including microcrack orientation, initiation, propagation, internal stresses, and macroscopic stress–strain behaviour to evaluate refractory ceramics’ resistance to thermal shock.