Failure and Fracture Characteristics of Al₂O₃ Ceramics under Impact Loading

As one of the typical brittle materials, ceramics are highly sensitive to deformation. Under strong dynamic loads, it exhibits mechanical response characteristics completely different from ductile metal materials which involve damage and destructive behavior. In this study, the split Hopkinson bar test system is used to carry out impact loading tests on Al₂O₃ ceramics obtaining the dynamic tensile/compressive properties of the ceramics, as well as the relationship of fracture characteristics with strain rate. In addition, the mechanical properties and fragment size of brittle ceramic materials under different strain rates are further studied by using the theoretical methods of energy conservation and dynamics. The results show that the tensile and compressive strength of Al₂O₃ ceramics is positively correlated with strain rate under impact loading. Furthermore, the particle sizes of Al₂O₃ ceramic samples vary greatly under the action of the one-dimensional stress wave. With the increase of loading strain rate, the total number of broken ceramic particles will increase and the average particle size will decrease, while the influence of stress concentration will gradually weaken. Finally, the fragment size of brittle materials simulated by the DID model is consistent with the experimental results. However, Grady model is derived from the fact that the generalization of ductile materials is quite different from the experimental results.