Application of Smoothed Particle Hydrodynamics in analysis of shaped-charge jet penetration caused by underwater explosion

A process of target penetration by a shaped-charge jet includes three main stages: charge detonation, formation of a metallic jet and its penetration of the target. With continuously increasing computational power, a numerical approach gradually becomes more prominent (combined with experimental and theoretical methods) in investigations of performance of a shaped-charge jet and its target penetration. This paper presents a meshfree methodology - Smoothed Particle Hydrodynamics (SPH) - for a shaped charge penetrating underwater structures. First, a SPH model of a sphere impacting a plate is developed; its numerical results agree well with the experimental data, verifying the validity of the mentioned developed method. Then, results obtained for different cases for various materials of explosives and liners - are discussed and compared, and as a result, more suitable parameters of the shaped charge in order to increase the penetration depth are obtained - HMX and copper were chosen respectively as the explosive and the liner material. It follows by validation of a model of a free-field underwater explosion, developed to verify the effectiveness of the modified SPH method in solving problems of underwater explosion; its numerical results are compared with an empirical formula. Finally, the SPH method is applied to simulate the entire process ranging from the detonation of the shaped charge to the target penetration employing the optimal parameters. A fluid around the shaped charge is included into analysis, and damage characteristics of the plate exposed to air and water on its back side are compared.