Research on the necking effect of pulse current on Shaped-charge Jet in passive electromagnetic armor

When Shaped-charge Jet (SCJ) penetrates front armor and approach to back armor, powerful pulse current flows it immediately and produces θ magnetic field simultaneously. Due to the effect of electromagnetic force F = J × B, the necking of SCJ occurs and leads to the breakup of SCJ into individual fragments and the penetration capability of SCJ is decreased significantly. In this paper, in order to improve defense capability of the passive electromagnetic armor against SCJ, the necking mechanism of the high-temperature SCJ is studied through Maxwell´s equations and elastic-plastic constitutive equations. A 3-D simulation model, supposed to be sine-disturbance and axial-symmetry, is developed to analyze the necking law of SCJ through electromagnetic-structure co-simulation. Take the skin-effect of pulse current into account, the distribution of current density, magnetic field, magnetic force and stress field are obtained through electromagnetic-structure co-simulation by finite element software, and the SCJ deformation is also calculated. The results indicate that, a powerful pulse current can accelerate the break-up of SCJ. At last, defense experiments of the passive electromagnetic armor against SCJ with high explosive anti-tank cartridge proceeded. The results demonstrate that, the penetration capability of SCJ with pulse current is lower than that without pulse current, and the penetration capability of SCJ declines remarkably with the increasing of charging voltage.