Abstract: The end cap thickness is an important factor to be considered in the accurate design of fragmentation warheads, so this study focues on the initial velocity distribution of fragments from cylindrical charge shell with different thick end caps, which is detonated at the center of one end. Based on theoretical analysis and SPH numerical simulation, the models of cylindrical shells are established, and then the theoretical formula of axial distribution of the initial fragment velocity is proposed. The results show that, with the increase in thicknesses of two end caps, the effect of axial rarefaction waves decreases, and the fragment velocity near the two ends increases accordingly. The acceleration effect of detonation products is the main cause of the velocity increase of fragments near the detonation end, while the acceleration effect of detonation waves is the main cause of the velocity increase of fragments near the non-detonation end. Compared with the fragments near the detonation end, the acceleration of the fragments near the non-detonation end is more apparent. The proposed formula is more suitable for end caps and materials in engineering and the relative error can be significantly reduced. The findings of this study can provide reference for the accurate design of warheads.

Key words: ordnancescienceandtechnology, initialfragmentvelocity, Gurneyequation, axialrarefactionwaves, numericalsimulation