Force-Electricity Matching And Ignition Characteristics Of Magnetoelectric Multifunctional Projectile Impacting Target

In order to achieve efficient damage to low,small and slow UAV targets,aiming at the urgent needs of modern battlefield environment for miniaturized and multi-functional projectiles with force-heat-electromagnetic and other functions,this paper adopts a new design concept to develop a new type of small-caliber multi-functional projectile.The magnetoelectric self-powered ignition system that produces high overload by penetrating the target is used to ignite the small-caliber multi-functional ammunition of the active material inside the projectile,focusing on the magnetoelectric self-powered electricity output characteristics of the multi-functional projectile under the impact load and the ignition characteristics of the active material inside the projectile.The joint simulation and experimental verification of ABAQUS / Explicit software and ANSYS Maxwell software were used to analyze the force and motion of the magnet and the projectile during the penetration of the target plate under different impact loads,and the relative motion velocity of the magnet and the coil was obtained.The effects of loading speed,geometric parameters of permanent magnet and coil turns on the electrical output energy and ignition delay characteristics of self-powered ignition system were obtained by improved SHPB experiment and impact ignition experiment,and the ignition reliability was evaluated.The main research contents and conclusions of this paper are as follows :(1)The projectile structure(shell,Al / PTFE active material loose powder and self-powered ignition system)was designed.Al / PTFE active material loose powder with mass percentage of 26.5 % / 73.5 % was prepared by self-developed mixing process.The experimental system of multi-function projectile penetrating target plate is constructed.The motion law of magnet in the projectile is obtained by joint simulation.The results show that the acceleration of magnet is very small,and the initial velocity of projectile is basically maintained during the whole penetration process.The relative velocity of projectile and magnet is mainly determined by the velocity attenuation in the process of projectile penetrating target plate.According to the variation of magnetoelectric induction intensity B with time,the coil parameters such as coil thickness,permanent magnet size(height,diameter),permanent magnet-coil initial spacing(tangential spacing,normal spacing)are preliminarily determined.(2)The design and optimization of the electromagnetic unit structure of the self-powered ignition system are completed by using the finite element simulation software Ansys Maxwell.The results show that the height or diameter of the permanent magnet should be increased as much as possible.Coil turns in 180 turns,coil thickness of about 1.5 mm is more appropriate;under the premise of satisfying the structural strength,the permanent magnet-coil spacing of 1mm is more appropriate.The influence of impact load and geometric parameters of magnet coil on the current in the external circuit of self-powered ignition system is clarified.When the permanent magnet moves inside the coil,the energy conversion efficiency is very low,and the induced electromotive force is the largest when the upper and lower ends of the permanent magnet just enter or leave the coil.The ignition time can be adjusted by adjusting the initial relative distance between the magnet and the coil.The speed change has a great influence on the induced electromotive force,which leads to the delay time change of the ignition system.The ignition threshold energy of the military electric igniter used in the experiment was calculated to be between 0.29 and 0.35 m J.When the diameter of the coil and the magnet is constant,the ignition threshold speed decreases with the increase of the magnet length.(3)The experimental projectile was improved,and the impact ignition test was carried out by loading the projectile with a first-stage light gas gun.The process of the projectile impacting the target plate and the movement of the magnet during the penetration of the projectile were analyzed,and the ignition characteristics of the magnetoelectric multifunctional projectile were clarified : The shortest ignition delay time of the self-powered ignition system in the experiment was 139μs,and the longest was 485μs;the loading experiment of the multi-function projectile impacting different targets is carried out.The projectile can reliably ignite when hitting different targets at a suitable speed.The multi-function projectile has good killing,armor piercing and arson capabilities.(4)The influence of gravity on the ignition reliability of self-powered ignition system during penetration was analyzed by numerical simulation of multi-function projectile penetrating target plate at different angles and velocities.The influence of penetration angle,velocity and other parameters on the penetration process is analyzed.The results show that gravity has little effect on the penetration process.the penetration depth increases at the same time,the maximum penetration depth increases;with the increase of projectile velocity,the penetration depth increases;as the angle increases,the penetration depth decreases;the movement of the magnet has a great influence on the penetration angle of the projectile during the oblique penetration process.The projectile falling from 37 m will not ignite the ignition head.