Velocity characteristics of fragments from prismatic casing under internal explosive loading

In this study, a prismatic casing, which is a part of a variable geometry device, is designed to improve the effectiveness of its impact distribution. The fragment velocity of the casing is investigated experimentally by high-speed photography. The experimental data indicate that the fragment velocities are influenced by the rarefaction wave from both the axial and transverse directions. In addition, the Parallel for Multi-material in Cell 3D (pMMIC-3D) hydrocode, coupled with the Lagrangian marker-point weighted method, is used to numerically investigate the fragmentation process of the prismatic casing. The numerical results confirm the considerable influence of the rarefaction wave on the fragment velocity. Therefore, a correction formula is proposed to calculate the initial fragment velocity on the basis of the experimental data. The agreement between the numerical results and corrected results confirms that the correction formula can be used to predict the fragment distribution of such prismatic casings.