Dynamic Behaviors For Alumina Ceramics Under Planar Shock Compression

Ceramics were widely applied in military and civil fields because of their excellent mechanical and physical behaviors. The behaviors of ceramic materials under shock-loaded were different with ductile materials. Therefore, research what focus on dynamic response of ceramic materials became the most active theme in dynamic mechanics domain in recent years. Achievements have been obtained about failure mechanism, constitutive relations and experimental measurements of ceramic materials.In this dissertation, plate impact experiments for polycrystalline alumina ceramics were proposed and performed on the basis of the research on dynamic behaviors of ceramic materials. The physical and mechanical response of alumina ceramics under shock-loaded were analyzed and discussed by the plate impact experiments. The main work and conclusions in this dissertation are as follows:â‘ Advance what have been made in recent years about failure mechanism and physical and mechanical behaviors of ceramic materials under shock-loaded were reviewed in this dissertation. The physical mechanism of failure wave formation and propagation, mechanical characters, failure criterion and constitutive models were review as the focus.â‘¡The basic physical and mechanical parameters of alumina were measured in ultrasonic experiments. The microstructures were analyzed by scanning electron microscope (SEM). The microstructures of alumina were strongly heterogeneous in mesoscope.â‘¢In the plate impact experiments of double alumina specimens with the light gas gun, free surface velocity histories of particle in different thickness alumina specimens under 1D-strain were measured by VISAR. The Hugoniot Elastic Limit for different thickness alumina specimens were calculated from the experimental results. Hugoniot Elastic Limit decreased along with increase of the specimen thickness. The recompression phenomena have been found in the particle velocity histories of alumina specimens while the impact pressure between 6GPa-8GPa. From the point of view of phenomena, the recompression signals in terms of free surface particle velocity occurring in alumina ceramics under shock-loaded were similar to those in glass where failure wave has been widely verified.â‘£The modified form for the Hugoniot Elastic Limit was given associated with Drucker-Prager yield criterion and strain rate. Hugoniot Elastic Limit of A95 ceramics were given by using the modified form of Drucker-Prager yield criterion. Comparisons were made between the calculational and experimental results.