Study On Action Mechanism Of Energetic Projectiles And Inertia Excitation Characteristics Of Charges

To improve the damage performance of the air defense warheads,this paper proposes an inertially excited energetic projectile kill element.According to the different modes of action of the inertial body on the charge,an explosive energetic projectile with a different structure of the inertial body was designed.Using the methods of theoretical analysis,numerical simulation and experimental research,the action process and the excitation mechanism were studied.Considering the effectiveness of the projectiles,the key factors affecting the timing of initiation of explosive energetic projectiles were compared and analyzed to provide the basis for the structural design of explosive energetic projectiles.Meanwhile,according to different damage targets,the charge of combustion energetic projectiles was explored.The ignition charactestics of Al/PTFE reactive materials were studied by using experimental research and numerical simulation,which provided references for the application of combustion energetic projectiles.The main work of the text is as follows:(1)The inertial excitation characteristics of energetic projectiles and the initiation characteristics of explosives were analyzed.Considering the mechanical response characteristics of inertially excited energetic projectiles passing through the target,the inertial characteristics of the inertial body on the charge were analyzed.Based on the impact ignition of explosive,the critical initiation criteria for explosives were deduced for high-velocity impact initiation and low-velocity impact initiation of explosives.According to the relative slip characteristics of the tip-shaped inertial body and the charge,a one-dimensional friction initiation model was established to provide the theoretical basis for the initiation mechanism analysis of the tipped inertial projectile during penetrating.(2)The impact initiation experiments of explosive energetic projectiles were carried out.Considering different initiation mechanisms of projectiles with the different inertia bodies,two types of energetic projectiles were designed by choosing the initiation characteristics of the charge under different inertial bodies.The critical initiation conditions of the two types of projectiles were obtained by the"up-down"method.Through high-speed video analysis of the projectile detonation process,it was found that the inertial body of the double-tapered structure can achieve the target of post-target energy release.At the same time,the initiation time range of the projectile is determined to provide a numerical analysis data support of the subsequent initiation mechanism.(3)The initiation characteristics of explosive energetic projectiles were analyzed numerically.Based on the particularities of explosives,a comparative analysis of the impact response characteristics of explosives were carried out by using different algorithms,which verified the superiority of the FEM-SPH coupling algorithm in simulating the impact response characteristics of particles and viscoplastic explosives.By the numerical simulation research of the penetrating process,the critical threshold of initiation for the passivated RDX explosive was determined.On this basis,the intiation method of the double-cone inertial body is determined as the relative sliding friction initiation between the inertial body and the charge.The dynamic friction coefficient with the passivated RDX charge is 0.04.(4)The factors affecting the initiation time of explosive energetic projectiles were analyzed.The effective damage of explosive energetic projectiles was reflected in the timing of the energy release of the charge.Based on the process analysis of penetration,the key factors affecting the initiation time were analyzed,including the nose shape of projectile,the structure of inertial body,the velocity of projectile and the angle of impact.The initiation times of projectiles were calculated by the numerical analysis of the impact response characteristics in different conditions.And then,the optimal projectile structures and the penetration states were obtained by the analysis of initiation position.(5)The impact ignition characteristics of Al/PTFE reactive materials were analyzed for the combustion energetic projectile charge.According to the effect characteristic of the inertia force,the impact ignition test of the reactive material was designed,and the Al/PTFE reactive materials with different compactness were loaded by chamber pressure generator.The results show that the critical ignition pressure of Al/PTFE reactive materials was 1.44GPa at a loading rate of 300MPa/ms,and the compactness has a little effect on the ignition pressure.At the same time,according to the discontinuity of the mesostructure of the reactive materials,the reactive material was microscopically modeled using a random particle generation method.Through the impact loading analysis of the meso-scopic model of Al/PTFE reaction material,the ignition mechanism of the reaction material under the gradually increasing impact load was revealed.