Effects of end caps of cylindrical casing on fragment velocity distribution

Fragment velocity distribution is an important parameter affecting the terminal effects of warheads. The rarefaction wave, end cap, and its confinement state can significantly affect the fragmentation of the cylindrical charge casing. Most of the existing studies have performed experiments and simulations considering the rarefaction wave and unfixed end caps; research on fixed end caps and sufficient theoretical explanations are limited. In this work, the effects of rarefaction waves, end caps, and their fixed states, on the fragment velocity distribution, were studied via experimentation and simulation, and reasonable theoretical explanations were provided. The results show that the rarefaction wave and end caps affect the fragment velocity by changing the pressure states of the detonation products. At the initiation end, the fragment velocities of casings with unfixed initiation ends are 33.3% (300 m/s) greater than that of casings without end caps, because of the weakening of the attenuation effect of the rarefaction wave. The fragment velocities of the casings with fixed initiation ends are 8.3% (100 m/s) greater than that of casings with unfixed initiation ends. At the non-initiation end, the fragment velocities are 24.8% (297 m/s) greater than that of a casing without end caps, and the reflecting shock wave generated by the fixed non-initiation end increases the fragment velocity by 7.3% (113 m/s), compared to the theoretical velocity. This work provides a basis for the structural design and analysis of the terminal effects of warheads.