Gerasimov A.V.   Пашков С.В.   Khristenko Y.F.  

Single and group strikes of high-velocity elements in a spacecrafts

Reporter: Gerasimov A.V.

The presence in a near-earth  layer (a  width of 300 to 2,000 kilometers), a huge number of man-made fragments of various sizes and shapes, which were formed in the process of destroying the satellites, the last stages of carrier rockets, boosters and other vehicles and equipment, represents a serious threat to the security of automatic and manned space objects. The problem of high-speed  interaction of designs with projectiles now acquires particular importance due to the increasing speed of the collision, which increases the likelihood of penetration, destruction and disruption of the normal functioning of the protected objects.
In recent years, particularly acute problem of reliable protection of elements of manned and automatic machines to study of  near-Earth and deep space due to the increasing duration of flight of these objects, which increases the likelihood of collisions with man-made fragments  that emerged as a result of the destruction of the orbital structures. Creating a reliable spacecraft protection from space debris fragments determines the necessity of studying the interaction of  a high-speed elongated strikers with securable objects.
Numerical simulation of high-speed interaction of solids with protective systems able to reproduce the characteristics of the physical processes occurring in the collision, to consider and select the optimum  screens of protection. Application to the study of the problems of modern computers and numerical methods to solve the problems of high-speed collisions in a three-dimensional setting, taking into account the fragmentation of projectiles and protective elements of spacecraft design, it is theoretically and practically important task. Accounting fragmentation and interaction of fragments with each other and with the spacecraft shell allows a better understanding of the processes taking place at high speed interaction of space debris with a shell of the space object. To solve this problem it is necessary to have a reliable and sufficiently universal method to enable adequate reproduction of the processes occurring in solids under high- velocity collision.
In this paper we consider the interaction of single projectile and groups of projectiles s with systems layered spaced plates. It should be noted that for practical problems of great interest are spaced obstacles and hit at an angle. For the numerical solution of these problems we need a reliable and sufficiently universal method to adequately reproduce the processes of destruction and fragmentation occurring in solids at high speed interaction.
A probabilistic approach to fragmentation of solids under shock loading and proposed  numerical technique to the fullest three-dimensional formulation allows with sufficient accuracy to reproduce  of the processes of penetration of high-speed elements into   multi-layer barriers and spaced barriers. Accounting  fragmentation of solids at intensive dynamic loading allows you to use the approach Lagrangian  to the problems of high-speed impact in  a fairly wide range of speeds interaction. This approach is especially useful when considering the multi-contact interaction of colliding bodies, especially for the  three-dimensional problems. Primary heterogeneity heterogeneousity of structure of real materials affects the character of the distribution of physical and mechanical characteristics of the material and is an important factor in determining the nature of the fracture.
One way to account for this fact is the introduction into the equations of solid mechanics random distribution of deviations of the initial strength properties   from the nominal value, that is, simulation, thus the structural features of the initial material, namely, the presence of pores, inclusions, dislocations, etc.
The probabilistic approach proposed and numerical technique developed on its basis enable us to simulate the processes of barrier breaking in a wide range of angles of impact. The calculations  fully have simulated of the field  of fragmentation and have taked into account the interaction of fragments with each other and with the elements of  multi-layer barrier, which is extremely important in the calculations for the protection of spacecraft, since the stream  of high - velocity  particles may penetrate the main body of the apparatus and this can damage equipment. Therefore, the kinetic energy of the fragments is necessary to evaluate  and calculate the process of collision with the main body. The proposed approach allows us to investigate the entire process of the interaction of projectiles and targets, taking into account the formation of fragment flow and the impact of the latter on the protected object.
The paper compares the effectiveness of the impact of the group of projectiles and we made an assessment of their impact on the degree of damage obstacles. The calculation results showed greater risk of exposure to the group of rods for the protecting shell of the spacecraft relative to the impact of a single projectile with a mass equal mass of seven percussionists, and the same rate.
The developed numerical method allows to simulate the interactions of shells spacecraft with high-speed long rods in a wide range of speeds and angles of impact, and also to investigate the processes of fragmentation barriers and a nature of fields of fragmentation . These results allow us to optimize  protection of objects .