Research On Diffusion Characteristics Of Nested Structure Projectile In High-Velocity Impact

With the continuous improvement of aerospace technology,the components and materials used in spacecraft are becoming more and more diverse.At the same time,the composition and structure of space debris are becoming more and more complex.When the spacecraft explodes and disintegrates,the soft and heat tolerant polymer materials are likely to combine with small metal fragments and large metal sheets to form a kind of space debris with nested structure.This kind of space debris has unique diffusion characteristics in high-speed impact,which is a special threat to spacecraft.Therefore,this paper designs a nested structure projectile to simulate this kind of space debris,and obtains its diffusion characteristics under different impact conditions through a large number of numerical simulations.The structural characteristics of nested structure projectiles are described by the thickness of fragment layer,the ratio of projectile length to diameter and the ratio of core diameter to projectile diameter.The impact simulation of single-layer target plate is carried out by projectiles with different structural characteristic parameters.The axial residual velocity,fragment diffusion angle and plate damage of the projectiles in the simulation results are analyzed,and the influence law of the nested structure characteristic parameters on the impact diffusion characteristics of projectiles is obtained.The results show that the ratio of length to diameter and the ratio of core diameter to projectile diameter have an effect on the axial residual velocity,and the outer diameter of the projectile,the thickness of the fragment layer,the ratio of length to diameter and the ratio of core diameter to projectile diameter all have an effect on the fragment diffusion angle.The impact simulation of multi-layer plate protection structure with different protection structure parameters,such as shield layer number,plate thickness distribution and plate spacing distribution,is carried out,and the influence rules of different protection structure parameter configuration on the protection effect of nested structure projectile and the final diffusion characteristics of the projectile are analyzed.The results show that the reasonable configuration of the protective structure parameters can make the projectile break up earlier and spread in a large range,decelerate and intercept the fragments to the greatest extent,so as to reduce the damage of the nested structure projectile to the spacecraft.The redundant structure of the front end of the space debris with nested structure is simulated by the head structures with different shapes,such as flat head,conical head and oval head.The single-layer target plate and double-layer aluminum bumper protection structure are impacted respectively,and the influence law of the head structure on the diffusion characteristics of the projectile and the protection effect of the protection structure is obtained.The results show that different head structures have different degrees of inhibition on fragmentation and diffusion of nested structure projectiles,thus affecting the diffusion characteristics of nested structure projectiles when they impact the protective structure.