Research On The Formability Of EFP And Its Terminal Effect

As a technology of inversing solidity target,the EFP play an important role in the weapon system of terminal-sensitive projectiles.The requirement of EFP technology become more higher with the rapid development in new-style protection technology.In order to coping with different target in different situation,many EFPs are appeared which is formed in different structure shaped charge liner.The damage ability of EFP becomes more rapid more far and more accurate by changing the geometry of shaped charge liner and charge structure.The flight stability of EFP will directly affect attacking precision in the condition of high stand-off.How to guarantee the flight stability under long distance becomes a difficult point of restricting the applicttion of EFP technology further.Fins is able to enhance the flight stability,so many researchers realized EFP with fins by using of various methods including multi-point initiation,special-shaped shell,wave-shaped and three-dimensional liner. This paper presents a way to form fins by using of pasting clapboard.The structural shape of detonation wave front is changed by clapboard which is affixed on the liner, then the detonation pressure on the liner results in regular changes which lead to form EFP with fins.The influence law of velocity and pressure on liner is anlysised in the theory,and then the feasibility of clapboard methods is confirmed by anlysising the influence law. The EFP with four fins is obtained by recovery experiment.Four piece of aluminium as a clapboard material is symmetrical affixed on the liner in this experiment.The numerical simulation on clapboard methods forming fins is simulated by LS-DYNA according to the condition of the experiment.Based on the results of the numerical simulation,some liner infinitesimal elements with a certain reperesentativeness is selected.The feasibility of clapboard methods is anlysised further from the velocity and pressure curve on the liner.Based on the energy conservation and momentum conservation,combined with different geometry of shaped charge liner,compared with experiment and numerical simulation results,two engineering algorithms and the application range of EFP are comparative analysised.The calculation method of EFP velocity which is formed by clapboard methods is derived,at the same time;the results between theoretical calculation and numerical simulation are compared.The velocity of EFP is an important index to assessment on the penetration power,so it is very important to anlysis the influencing factors of the EFP's velocity.Based on the calculation method of EFP,the velocity of large cone angle liner of twelve different schemes is calculated in the theory,combined with the results of numerical simulation,the influencing factors of the EFP's velocity are anlysised by grey theory,and the grey correlation degree matrix between the EFP's velocity and every influencing factors is established, then the major influencing factors are obtained.It is a very complex physical and mechanical process about the EFP penetrating target plate.The process is different from the rigid projectile body and high velocity jet penetrating target plate which lies between them.The penetration performance of EFP with fins and pseudo-spherical EFP are researched by experiment,and the whole process of the EFP penetrating target plate is obtained by numerical simulation,at the end,three typical stages of penetrating process is anlysised in detail.The study on effective charge has a very important significance in increasesing the ratio of energy utilization and reducing the weight of warhead.How to obtain the maximum kinetic energy under reasonable designing the charge structure has a certain research value in optimization designing the EFP warhead.The large cone angle liner is taken as a research object,combined with theoretical analysis and numerical simulation on effective charge.The change law of EFP's velocity,kinetic energy and the ratio of energy utilization are anlysised which is obtained by the large cone angle liner under different length-diameter ratio of shaped charge.At the last, the numerical simulation about different ship-tail shaped charge is calucated by LS-DYNA and corresponding optimization scheme of charge structure is presented.