New Formula for Fragment Velocity in the Aiming Direction of an Asymmetrically Initiated Warhead

Abstract

Fragment velocity is an important parameter for fragmentation warheads, but for an asymmetrically initiated warhead, formulas for calculating the fragment velocity in the aiming direction are rare. In this work, new formulas for calculating fragment velocities in the aiming direction and the initiation side of an asymmetrically initiated warhead were established by taking the long element from the warhead section and applying one‐dimensional gas dynamics. Accounting for the assumptions made during the formulas establishing, three experimentally verified warheads modelling of different charge ratios were used to verify the formulas. It is found that the velocity ratios of the modelling to the formulas’ calculations of different warheads are very similar. Hence the fitted curves for the velocity ratios versus the warhead charge ratios were used as correction factors for the established formulas. Finally experiments were designed and conducted to validate the revised formulas, which shows acceptable relative errors of 2.8 % and 9.9 %, better than already existing formulas. The established formulas could be a good reference for the damage evaluation of aimable warheads and for fragment velocity distribution research.

Fragment Velocity Formula for Reverse Detonation Driving with Opposite Initiation

“…and 1045 steel casing, as depicted in Figure 3. The density of the explosive charge is 1.834 g/cm 3 , with a detonation velocity of 8695 m/s.…”

Fragment Velocity Characteristics of Warheads with a Hollow Core under Asymmetrical Initiation

“…It was proven that the warhead cylinder could be considered as a two-dimensional plane strain problem when the effects of the rarefaction waves from the ends of the warhead were ignored [20]. Previous studies [9,21] showed that the 2D SPH method of AUTODYN could be used to investigate the fragment velocity characteristics of warheads under asymmetrical initiation. Therefore, in the present work, the 2D SPH method of AUTODYN was adopted to simulate the explosive fragmentation process, and the initiation points represented the initiation lines in the 3D structure of the warhead.…”

“…The second group of warheads came from Li's experiments [9]. The explosive charge was 8701 explosive (1.67 g/ cm 3 , detonation pressure 29.7 GPa, detonation velocity 8100 m/s), and the metallic casing was AISI 1045 steel (7.85 g/cm 3 ).…”

“…Table 1 shows the fragment velocities both in the aiming direction and on the initiation side. The material parameters in our simulation were taken from references [9,25]. The particle size was again set to 0.15 mm to both ensure simulation accuracy and control computation time.…”

“…The above formulas for calculating fragment velocities of aimable warheads are all based on limited experimental and numerical results, or their wide applications are limited. Therefore, Li [9] proposed new formulas for calculating the fragment velocity in the aiming direction (Eq. (2)) and that in the initiation side (Eq.…”