Coupled Thermo-Mechanical Phase-Field Modeling to Simulate the Crack Evolution of Defective Ceramic Materials under Flame Thermal Shock

Crack propagation in ceramics is a highly quick, complex, and nonlinear process that occurs under thermal shock. It is challenging to directly observe the evolution process of cracks in experiments due to the high speed and unpredictability of crack propagation. Based on the phase-field fracture method, a phase-field numerical model combined with thermal and mechanical damage is established to analyze the crack propagation path, velocity, and morphology of pre-cracked ceramic plates under flame thermal shock loading. This research primarily focuses on the impact of prefabricated crack angle and length on crack propagation. According to the findings of the numerical simulation, ceramic plates with varied prefabricated crack angles are loaded via flame thermal shock, and thermal stress is caused by the rapid rise in the temperature difference between the top edge and the inside of the ceramic plate. Hence, the crack propagation rate seems to be quick at first, and then, slows down when the wing-like cracks at the crack tips spread to both ends. The crack tip on the side closer to the flame thermal loading is more likely to generate wing-shaped cracks as the length of the pre-existing crack increases. However, the crack tip on the side further away from the flame thermal loading exhibits the reverse tendency. The complex evolution process of crack initiation, propagation, and coalescence in ceramic materials brought on by flame thermal shock can be predicted by the thermo-mechanical coupled phase-field model, which is a valuable reference for designing and optimizing the thermal shock resistance and mechanical failure prediction of ceramic materials.