Research On Dynamic Characteristics Of Projectile-fuze System In Concrete Penetration

In detonation physics,weapon physics and Engineering Physics,the dynamic process and structural response of projectiles penetrating into concrete targets are always the frontier topics in this field.The in-depth study of the dynamic characteristics of the bomb-fuze system provides effective technical support for the fuze to identify the external environment and effectively strike the target.In this paper,the acceleration signal of the projectile-fuze in penetration concrete target was taken as the research object.Based on the finite element simulation technology and experiment method,the mechanism and structural response analysis of projectile penetrating concrete target ware studied.The function and influence of the threaded structure between the projectile and fuze,the installation mode of the missile-fuze and the impact posture of the projectile on the dynamic characteristics of the missile-fuze system are analyzed.The main work content and research conclusions are as follows:The process of projectile penetrating into the concrete target plate and the formation mechanism and composition of the acceleration signal are analyzed.Finite element model of missile-fuze system with intact internal structure was established.Through the modal analysis of missile-fuze system,the natural frequencies and mode shapes of the system were obtained.One-stage light gas gun test was conducted and the test results were applied to frequency domain analysis of the acceleration signals of the system’s internal sensors.It was high identical between the peak frequency and natural frequency of modal results,which fully proved the reliability of finite element model.It shows that the natural frequency of the axial tension-compression mode of the system has a great influence on the vibration characteristics of the system.The process of building the finite element model of the missile-fuze system with solid thread and simplified thread with a complete internal structure was introduced.Comparing the calculated results by the finite element model with the experimental data,it is shown that in the numerical simulation,the simplified thread structure between the projectile and the fuse can not accurately reproduce the actual penetration overload,and it is confirmed the shock absorption characteristics of the thread structure in the penetration environmentBased on the numerical simulation technology,the axial stress and stress transfer of the thread structure during the impact process was analyzed.It shows that there is a certain correspondence between the acceleration signals of the structure and the thread stress in time.It is concluded that stress transfer speed is almost unchanged at different locations in the structure at the beginning of stress.One missile-fuze installation structure with ring-screw was designed,which was compared with the traditional body threaded projectile structure by the time-domain and frequency-domain analysis of acceleration signal.The vibration amplitude of the overloading signal of the missile-fuze system with ring-screw structure of the penetration result was smaller and the signal response was fast.It indicates that the ring-screw-type missile-fuze installation structure is better than the body screw type.Through the analysis and comparison of the simulation results of different striking angles,it is shown that the vibration of the overload curve on the deflection direction increases with the increase of the initial striking angle of the projectile,and the vibration of the overload curve decreases in the penetration direction.By analyzing the process of penetration at different angles of attack,it is shown that the influence of angle of attack on the acceleration signal of the system is almost invariable when the angle of attack is increased from 2 degree to 4 degree.