基于离散元法分析增韧陶瓷圆环的动态膨胀碎裂

The dynamic expansion fragmentation of ceramic is numerically simulated to study the impact tensile fracture of ceramic with high strength and brittleness. The free expansion motion of toughened ceramic ring at high strain rate is studied using flat-joint contact model based on the discrete element method, from which the variation laws of particle motion velocity and system energy during the expansion and fragmentation process of ring are obtained. The results show that, before the ring fracture, the radial velocity of inner particles presents an increasing jump in the middle layer, while the radial velocity of outer particles presents a decreasing jump. The velocity jump is related to the rigidity of ceramic ring, but not to the initial loading velocity, at the moment of ring fracture, the release of strain energy is accompanied by the formation of unloading wave in the ring. Due to this fact, the radial velocity of outer particles presents an increasing jump, while the radial velocity of inner particles presents a decreasing jump. This velocity jump phenomenon is helpful to determine the initial brittle fracture time of the ring in the experiment; the normalized size of ceramic fragments decreases with the increase in normalized strain rate, which is in good agreement with the theoretical model in Ref.[17-18].