Mechanism analysis and prediction of explosive formed projectile’s axial fracture

Abstract

To explain the axial fracture phenomenon of Explosively Formed Projectile (EFP), the fracture mechanism of long rod EFP during the forming phase is analyzed by the stress wave theory. When the velocity gradient [Formula: see text] between the head and tail parts exceeds the critical value [Formula: see text], the EFP would fracture in the axial direction. Based on the Johnson–Cook constitutive model parameters and the special conditions in the forming phase of EFP, the critical velocity gradient [Formula: see text] can be determined by theoretical calculation and then validated by experimental results for both copper and tantalum EFPs. The experimental results for EFP’s fracture agree well with the prediction of the theoretical analysis. The theoretical analysis method can be applied as an important measure to determine the critical velocity gradient and predict the fracture of long rod EFP, providing reference for the application of new kinds of high density materials in the EFP research area.

Formation of an Explosively Formed Penetrator Warhead Using a Step-Shaped Charge

“…Baburin et al [13] developed a model for forming a tilted-fold tail EFP, studied the influence of the tail on the change in the aerodynamic coefficients for a wide range of head-on angles, and calculated the angular velocity of the axial rotation of the tilted-fold tail EFP based on Newton's method. Ding et al [14] used stress-wave theory to analyze the long-rod fracture mechanism of explosively formed projectiles in the forming stage and experimentally verified the critical velocities of copper and tantalum foil forming. Jie et al [15] investigated the formation mechanism of a double-curvature charge-hood explosively formed projectile under the effect of a positive oblique reflection overpressure.…”