Simulation of the thermal shock cracking behaviors of ceramics under water quenching for 3-dimension conditions

To overcome the limitations of widely used criteria, maximum principal stress and maximum tension stress, in simulating and evaluating thermal shock resistance of ceramics for 3-dimension (3D) problems, a temperature-dependent critical fracture energy density criterion was proposed based on the force-heat equivalence energy density principle for the 3D thermal shock fracture problems of ceramic materials in this paper. Taking advantage of the criterion and finite element method, the thermal shock behavior of water quenching of cuboid Al2O3 specimens with different temperature differences were simulated. The crack patterns of the simulation results were shown to be approximated in the experiments. Especially the essential features, the longitudinal main crack and crack branches, are embodied well in the simulation results. However, the thermal shock cracks obtained by using the criteria, maximum principal stress and maximum tension stress, failed to meet the experiments. The effects of water entry posture on thermal shock crack features revealed in the results confirm the efficiency of the criterion in 3D conditions of thermal shock fracture in this paper. Finally, the maximum temperature gradient, not maximum temperature difference, was found to be the main controlling factor which caused the fracture energy density to reach a critical value to produce thermal shock crack.