Numerical study of velocity distribution of fragments caused by explosion of a cylindrical cased charge

Abstract

This paper presents a study of the velocity distribution of fragments caused by explosion of a cased charge. Available formulas usually predict a uniform fragments velocity at the middle part of the cylinder and only few sources recommend evaluation of a non-uniform velocity distribution. According to few, yet available, experimental results, the latter distribution is more realistic. Three numerical simulation techniques were used in the work described here, to simulate the velocity distribution of a cased cylindrical explosive charge: 2D simulations, 3D simulations and 3D simulations using the SPH method. Additional simulation of a pre-formed fragmentation was also investigated. The failure and erosion criteria of the casing material have been examined in the numerical analyses. The results of the numerical simulations have been verified against reported experimental data, which indicated a non-uniform velocity distribution along the cylinder axis. Overall, there was a good agreement between the 2D, 3D, 3D-SPH methods and the experimental measurements, including the distribution of the lower velocity values near the cylinder edges. Conclusions of this study include characteristics of the velocity distribution and observations regarding advantages and disadvantages of the techniques that were used. It is shown that the velocity distribution can be described by a normalized ‘shape function’, which depends on the casing length-to-diameter ratio. Finally, it is noted that the mass distribution, which has been out of the scope of this study, should be investigated as well.