In order to determine the impact depth of a frustum projectile impacting a across stiffened plate vertically, the residual velocity of the projectile after penetrating the stiffened plate must be known. The plug is formed after the conical projectile penetrating the grillage and the cross section of the plug is similar to that of the conical projectile. The petal failure is formed on the panel. By the squeeze of the conical projectile, the web plate occurs plastic deformation and the alar plate cause turnover. Based on the failure model, the energy consumption mode of the grillage was determined. During the perforation process, the energy consumption of the grillage was completed by shear deformation of the plug, kinetic energy of the plug, plastic extruding deformation of the grillage, the power work of the petals, the propagation of radial cracks and petal bending. In the view of energy, the energy formula was deduced for each energy dissipation mode and the energy consumed in the impact process was determined. The residual velocity and the ballistic limit velocity of the projectile was deduced by energy conservation principle.The comparison of the analytical results of the residual velocity to the numerical results is excellent agreement, which verifies the accuracy and reliability of the theoretical formula.
The residual velocity of the conical projectile after impacting the plate decides its impact depth. This problem is of great interest in military field, for example, anti-ship projectiles resort their own kinetic energy to breakdown the outer side panel of the ship, and continue to intrude into the warship by residual velocity during delay time 5~10ms, and detonate their war-head. The outer shell of war-ship is constructed by stiffened plate. So the penetration of stiffened plate is the focus of attention by researchers.