EXPERIMENTAL STUDIES ON THE EXPANSION AND FRACTURE OF PROJECTILES UNDER HIGH POWER EXPLOSIVES

To acquire the fracture mechanism of warhead shells under high power explosives, three projectile materials: 30CrMnSiNi2A steel, 40CrMnSiB steel and 50SiMnVB steel were examined. By capturing static burst of the projectiles using an ultra-high speed camera, the expansion and fracture processes of the three projectiles were obtained. The radial expansion coefficient of projectiles was employed to derive the relationship between the radial projectile expansion and time, taking into consideration projectile material properties. In addition, the maximum initial velocities of fragmentation of the three materials were tested. It was found that, the velocity of projectile expansion and the initial velocity of projectile fragmentation of new materials were larger. Compared with the 50SiMnVB steel shell, the maximum initial velocities of projectile fragmentation were improved by 19.0% and 31.9% for 30CrMnSiNi2A steel and 40CrMnSiB steel, respectively. The distribution of initial velocity of fragmentation along the axis of the projectile was the same for different projectile materials, and the maximum initial velocity occurred at 70% of the projectile length away from the ignition point. This study is expected to provide guidance for material selection and design for fragmenting warhead shells.