Research On Damage Of Grooved MEFP To Target

In order to meet the need of modern war, the multiple explosively formed projectile(MEFP), developed on the traditional single explosively formed projectile (EFP), has the advantages of higher operational efficiency and bigger killing radius. In this paper, based on the ANSYS/LS-DYNA software, the influence of parameter of liner and shell to forming and damage of grooved MEFP was worked, to make the design of grooved MEFP better. The main study contents are as follows:Firstly, the study on the forming mechanism and the mode of damage to target plate of grooved MEFP was worked. The results are as follows:the forming process of grooved MEFP has five stages:flip, extrusion fracture, tensile fracture, cross spreading and steady flight; the process of damage to target plate mainly includes contacting stage, penetration stage and puncture stage; for sub EFP, if the head first touches the target plate, loss of energe is the least, if the middle touches the targer plate first, perforation area is maximum; if the tail first touches the target plate, its damage efficiency is the lowest.Secondly, the influence of the groove angle to the forming and damage of grooved MEFP was studied. The main groove angles that studied are 30°,40°,50°,60°,90°, 120° and 150°. The results of the study are as follows:When the groove angle is 30°or 90°, during the forming process of sub EFP, there is a breakage. The speed and the degree of flying apart of sub EFP increase with the groove angle. When the groove angle is from 30° to 60°, groove angle influences the change of speed of sub EFP deeply. When the groove angle is from 60° to 150°, groove angle influences the change of speed of sub EFP lightly. When the groove angle is 50°, sub EFP can complete the overall process of damage to target plate, but the residual kinetic energy of sub EFP is little. When the groove angle is 60°, sub EFP can complete the overall process of damage to target plate, and the residual kinetic energy of sub EFP is enough. The groove angle of 60° is the best to forming and damage efficiency of sub EFP.Thirdly, the influence of the size of the center hole to the forming and damage of grooved MEFP was studied. The size of the center hole (relative diameter) that studied are:0 (no center hole),1.3×10-2,1.94×10-2,2.58×10-2,3.23×10-2,3.88×10-2,4.52×10-2, 5.17×10-2,5.81×10-2and 6.5×10"2. The results of the study are as follows:When the relative diameter is 3.23×10-2, the forming of sub EFP and the damage efficiency of warhead is the best.Fourthly, the influence of the shell material to the forming and damage of grooved MEFP was studied. The main materials that studied are 45# steel, aluminum and copper. The results of the study are as follows:When the material is 45# steel, the sub EFP that formed, has higher flight velocity and flight stability, and its forming result is the best, its residual kinetic energy is maximum.45# steel is better than aluminum and copper to be the shell material of grooved MEFP warhead.Fifthly, the influence of the thickness of the shell to the forming and damage of grooved MEFP was studied. The main thickness of the shell (relative thickness of the shell) that studied are 3.23×10-2,6.5×10-2,9.69×10’2 and 1.292×10-1. The results of the study are as follows:When the relative thickness of the shell is 6.5×10-2, the sub EFP that formed, has a better forming result, higher flight velocity and flight stability and maximum initial kinetic energy and residual kinetic energy.