含预制裂纹陶瓷圆盘劈裂破坏的离散元模拟

To investigate the alumina ceramics’ crack evolution process under impact loading, a numerical simulation of dynamic Brazilian splitting for platform disc ceramics was carried out by the discrete element method. The discrete element particle flow software was adopted to establish the numerical simulation model of ceramic specimens in impact loading experiments. The crack evolution process and failure mode of specimens with different inclination angles (the angle between the prefabricated crack and the loading direction) under impact loading were analyzed. Combined with the stress field distribution at the tip of mixed mode crack, the initiation and propagation laws of wing crack were analyzed. The results show that the cracks in the platform disc specimen are produced in the center firstly, then the secondary cracks sprouted and expanded from the disc edge. The specimen finally shows a tensile damage pattern. The results of the discrete element simulations are consistent with the experimental phenomena of dynamic Brazilian splitting based on the SHPB device. When the inclination angle of the prefabricated crack is 0°～60°, changing the inclination angle can produce a mixed crack mode between type Ⅰ crack and type Ⅱ crack. And the main crack on the specimen is nucleated from the tip of the prefabricated crack and exhibits a winged crack extension type (the curvature of the extension tapers to zero). With the increase of the inclination angle of the prefabricated crack, the crack initiation angle increases, and the crack initiation stress shows a trend of decreasing firstly and then increasing. The specimens are most susceptible to cracking when the prefabricated crack inclination is 30°.