Analysis And Research On Factors Affecting On MEFP Molding

Ground crowded armored targets and aerial helicopter gunships are the mainassault force in the future war. Whether impeding and effectively destroying them ornot became the important factors that influence the situation of the war. The need ofmodern war cannot be satisfied by using traditional single Explosively FormedProjectile (EFP) warhead for point-to-point attacks. Forming MFEP barrage, MultipleExplosively Formed Projectile (MEFP) warhead can intercept incoming missiles atshort range and detonate them, attack cluster tanks and helicopter gunships densely sothat it can cause widespread damage to the target, effectively improve the damageefficiency of weapon system.Analysing the formation mechanism and formation mode of EFP according to themolding technology of MEFP warhead that have been researched at home and abroad,this paper proposes a kind of structural concept of double groove MEFP byprefabricating grooves and trepanning both inside and outside the liner. ApplyingPROE software, three-dimensional entity model of double groove MEFP can beestablished. Bringing the entity model into ANSYS/LS-DYNA which is a kind ofsoftware of finite element analysis, the numerical calculation about the formingprocess of double groove MEFP warhead can be done by ANSYS\LS-DYNA. With theparameterization of the factors, and changing a single factor, the influencing law offorming process of groove MEFP that caused by the factors can be researched.Specific jobs are as followed:Firstly, under the study of liner, fitting analysis of radius of curvature ratio andgroove depth is done. Steel, red copper and tantalum are used as liner material.One-sided and two-sided are the ways of grooving. There are six different radius ofcurvature ratio of liner and depth of groove. In the numerical calculation, the numberof groove ranges from3to6.The research results show that velocity of sub-EFP made from steel is the fastest, and that made from tantalum is the slowest, but length isopposite. In the same groove depth velocity of sub-EFP which is formed in one-sidedgroove is lower, flying angle is bigger, length is longer. When radius of curvature issmall, end skirt cannot open completely, and mass are focused on the head. Whenradius of curvature is big, the length of sub-EFP is too long. When groove depth is toodeep, three sub-EFPs which are formed during the process of forming of MEFPwarhead separate so prematurely that velocity gradient of sub-EFP is too large, anddegree of density reduces so that penetration performance reduces. Simple groovedepth goes against the formation of three sub-EFPs and velocity is low. When radius ofcurvature is from1.25to1.5and the groove depth is from1/7to1/5of liner thickness,formation and velocity of the sub-EFPs are optimal. With the groove numberincreasing, the number of sub of EFP is increasing, velocity reduces, and flying angleincreases. For heavy armor, the number of groove is4or5can make kinetic energylarger, and for light armor, the number of groove is6or7can make attack range wider.Secondly, under the study of powder charge, three kinds of high energy explosiveare TNT composition B and RXD. In numerical calculation, draw ratios of powdercharge are1,1.25,1.5and1.75.The research results show that, with detonationvelocity of explosive increasing, velocity of MEFP and sub-EFP increases. Velocity ofcomposition B is the fastest, RXD follows, and TNT is the slowest. With draw ratio ofpowder charge increasing, length of sub-EFP increases, but when draw ratio is over1.5,velocity of sub-EFP reduces instead of increasing.Thirdly, under the study of way of initiation, in the numerical calculation, ways ofinitiation are center initiation and three-point initiation. The research results show that,velocity of the sub-EFP is lower and flying angle is bigger, when it is center initiation.Finally, compare with the results of numerical calculation, experimental resultsare identical with computation results, which are both about forming velocity of MEFPand flying angle. Therefore, the design of double groove MEFP turns out to beworkable.