THREE-DIMENSIONAL NUMERICAL SIMULATION ON THE FORMATION OF EFP WITH CRACKS IN CHARGE

The EFP (Explosively Formed Projectile) charge design assumes that the charge is uniform and does not consider charge defects. However, in actual situations, the explosive charge will have crack defects due to the change of ambient temperature. Many experimental results show that the existence of cracks in charge will reduce the penetration capability of EFP, but there are no relevant reports to explain the mechanism. In this paper, the propagation mechanism of detonation waves in explosives with cracks is analyzed by means of theoretical analysis and numerical simulation. Taking the slope pattern crack as a typical crack shape for analysis, the three-dimensional numerical simulation was carried out by using the shock physics explicit Eulerian dynamics software SPEED, and the influence of crack structure parameters on the asymmetry of EFP forming was studied. Based on dimensional analysis, the relationship between crack inclination angle, position and the lateral velocity of EFP head was established. The analysis results show that due to the existence of cracks, there is the lateral velocity in the formation of EFP, and the lateral velocity of EFP increases with the increase of crack width, inclination angle and crack height. Due to the existence of the lateral velocity of the EFP head and the asymmetry of the EFP shape, its flight attitude is unstable, which in turn affects the penetration power.