Formation Mechanism And Design Technique Of High-Velocity Rod-Shaped Projectiles

A high-velocity rod-shaped projectile is characterized by high tip velocity, low stretching rate, and high ratio of length to diameter(L/D). It is formed by hybrid charge whose liner is an intermediate g eometry lying shaped charge and e xplosively formed projectile(EFP) charge. Hybrid charges can be easily integrated into all weapon systems because of their short L/D ratio, very low weight, and superior performance over shaped charge and EFP charge. As a main charge, the hybrid charge can defeat modern composite base armors, as a precursor, the hybrid charge can be adapted for use in tandem warhead systems with minimal interference to the following charge. Since 1990s the technology of hybrid charge escalated significantly, and is currently in production as part of a warhead system.In this dissertation, the mechanism of high-velocity rod-shaped projectile is studied by using theory, numerical simulation and experiment. The results are as follows. A shaped charge with wide-angle conical and tapered liner can produce a high-velocity rod-shaped projectile. The explosive is initiated by peripheral initiator achieved by the use of a multi-point initiator(MPI), and the liner has an opening at the top by cutting off the apex of liner. Under the explosive loading, the contour of collapsing liner is like as a trumpet, the top elements are directly driven to the symmetry axis and the bottom elements are folded rearward to the symmetry axis. All liner elements collapses on the axis and split into a very fast jet and a much slower-moving slug, which eventually separate from each other. Because the impacting angle increases and the wall thickness of liner decreases continuously from the cone top to the base, the diameter of the jet is large, the velocity gradient of the jet is low, hence a high-velocity rod-shaped projectile is formed.A shaped charge with tapered tulip liner can produce a high-velocity rod-shaped projectile. The explosive charge is initiated by peripheral initiator, and the liner has an opening at the pole by cutting off the top of liner. Under the explosive loading, the contour of collapsing liner is like as a mushroom, the liner is folded rearward, collapse on the axis and split into a very fast jet and a much slower-moving slug, which eventually separate from each other. Because the impacting angle increases and the wall thickness of liner decreases continuously from the pole to the base, the diameter of the jet is large, the velocity gradient of the jet is low, hence a high-velocity rod-shaped projectile is formed.Compared with the shaped charge with tapered tulip liner, the shaped charge with wide-angle conical and tapered liner whose projectile velocity is higher and penetration is deeper is a more reasonable selection for a high-velocity rod-shaped projectile.The computer code ASCC(Analytical Shaped Charge Code) was formulated from analytic expressions of detonation driving and jet formation. The performance of the ASCC code is best illustrated by presenting results of a calculation and comparing these results with experimental data or with results from other numerical techniques. The ASCC code was used to investigate the direct distributed parameter optimization of a nonlinear dynamic system using genetic algorithms. The investigation consisted of optimizing the liner contour required to produce a desired projectile profile in the least squares sense.The performance of numerical simulation is best illustrated by presenting results of a calculation and comparing these results with experimental data. Based on the numerical simulation, two optimization models are designed. The high-velocity rod-shaped projectile of Model I has a tip velocity of 4.32 km/s, a rear velocity of 3.64 km/s, a length of 103.3 mm, and a mass ratio of projectile to liner of 60% at f=100 (is. The high-velocity rod-shaped projectile of Model II has a tip velocity of 4.61 km/s, a rear velocity of 2.11 km/s, a length of 103.2 mm, and a mass ratio of projectile to liner of 83% at t=10 (as.The numerical studies of jetting projectile charge(JPC) are performed. A high-velocity rod-shaped projectile is formed from a copper liner with 100% of the liner mass transferred to the projectile. Compared with the projectile formed from the shaped charge with wide-angle conical and tapered liner, the JPC projectile has a lower tip velocity and velocity gradient.