Study Of Damage Effects Of Groove Type MEFP Based On ANSYS/LS-DYNA

Multiple explosively formed projectiles (MEFP) can effectively raise theutilization rate of explosive and the hitting rate. Damage effects of groove type MEFPwas studied in this paper. The main tasks are as follows:Firstly, the forming process of groove type MEFP and the process of penetrationdouble nonseptate steel target based on LS-DYNA were studied. The results show thatthe forming process of groove type MEFP should pass through five stages: overturn, thehead extrusion fracture, the rear tensile fracture, cross flying and stable flying. The crossflying is caused by the radial force which come from detonation wave. Penetrationprocess should pass through three stages: spud in stage, unite penetration stage andthroughout stage.Secondly, the influence of liner’s groove parameter on the dispersion angle andvelocity of groove type MEFP were studied. The results show that in the case of samegroove curvature radius of groove type MEFP, the dispersion angle increases withgroove depth, the speed decreases first, then increases, and then decreases; same topgroove depth of groove type MEFP, the dispersion angle increases with curvature radius,the speed changes little.Thirdly, to study the penetration ability and aftereffect of groove type MEFP topenetrate double and finite thickness’ steel target, the processes were calculated. Theresults show that each projectile rotates along the direction that deviates from axialspeed after splitting, different rotation speed leads to different attack attitude; if otherconditions keep equal, the larger thickness of liner is, the smaller axial speed ofprojectile is, the more wear of liner is, so the liner thickness exist an optimal valuebased on penetration ability; charging ratio of length to diameter has little effect toprojectile shape, groove depth is significant to projectile shape, the aftereffect ofshallow groove depth is better.Fourthly, the influence of initiation point number and location to groove typeMEFP were studied. The results show that in the case of initiation point number is7, theprojectile is not easy to be pulled apart and it’s shape is good. In the case of the initiation point number is same, the projectile axial velocity and dispersion angleincreases with the distance between initiation point and liner. In the case of the distancebetween initiation point and liner is1, the initiation point number is6/7, residualvelocity of projectile wear after the target is fast.Fifthly, to get effect pictures of groove type MEFP on formation and penetration,the influence of groove number on the formation and penetration of groove type MEFPwere studied. The results show that only the groove number less than10, the number ofprojectile and grooving is same; Groove number n has little influence on projectiles’axial velocity; only the groove number less than9, the projectiles be able to throughoutthe double1.5cm thick steel target.