Experimental and numerical study on the influence of explosive charge length on the performance of explosively formed projectiles

Abstract

Understanding how explosive charge length affects the formation and terminal performance of explosively formed projectiles (EFPs) is crucial for designing efficient warheads. In this study, a 54-mm EFP warhead comprising an oxygenfree high-conductivity (OFHC) copper liner and C4 explosive was investigated. Eleven configurations with charge lengths ranging from 0.7 to 1.7 times the charge diameter were analysed using ANSYS Autodyn simulations and the Modified Johnson-Cook model. An experimental test at l/d=1.2 impacting a steel target validated the simulation. The results show that projectile velocity, penetration depth, and diameter increase with charge length up to 1.2-1.4d, yielding EFPs with stable, aerodynamic shapes. Beyond this range, performance plateaus, marking the onset of geometric saturation where added explosive mass does not enhance the projectile’s kinetic energy. The experimental velocity deviated by less than 2.3% and the penetration diameter by less than 5.7%, indicating that the proposed model agrees well with the experimental results. These findings provide practical guidance for optimising EFPs warhead design.