3-D Numerical Simulation Of Hypervelocity Impact With Smoothed Particle Hydrodynamics

As human’s frequently space act, there are more and more debris in the space. The space debris are so numerous, hyper-velocity and anomalistic and mainly scattered in the perigee orbits. Human’s space actions are badly imperiled. Many spacecraft wrecks are brought by the debris. Therefore, the researches on hypervelocity impact and shield design are vital for the spacecrafts’safety. There are many other applications also, for examples, the kinetic energy rod warhead systems, anti-ballistic missiles technology, light armor design and astronomic aerolith impact, etc.Pressure induced by the solid hypervelocity impacting could outclass the material yield stress. In the initial phase of this process, the solid characteristics are similar to the compressible liquid, so the deformation solid in the initial stage of impact can be described by the governing equations of hydrodynamics, and they could be simulated by the conventional CFD methods. But at this stage, there are some difficulties that couldn’t be resolved easily by the traditional grid-based numerical methods, for example, large deformation, penetration and fracture. Grids may be severely distorted, and deformation interfaces or fracture surfaces are hard to be tracked. On the other hand, Smoothed particle hydrodynamics (SPH) method offers a possible solution to these difficulties. In this paper, some researches about SPH method and its applications are presented.In this thesis, we try to describe the hypervelocity impact theory, to study this problem by smoothed particle hydrodynamics method and to analysis the impacting interactions.In the preface of the thesis, the background and progress about hypervelocity impact and smoothed particle hydrodynamics are introduced at first. Then, a description was given about the work in the thesis.In the second chapter, some theories about hypervelocity impact and smoothed particles hydrodynamics method are introduced. Solid mechanics constitutive equations, Mie-Grunersen equations of state and Von Mises yield criterion are adopted in the process of the hypervelocity impact simulation.In the third chapter, the SPH code was developed and validated. The code process, particles initial setup method and boundary control are described. To improve the computation efficiency, the link-list search method and particles expand method were used. Then, we simulate some typical impacting examples, such as steel tyler bar impact, thick steel plate impacted by steel projectile and thin copper plate impacted by copper projectile. Compared with the experimental results, some satisfied agreements are obtained.In the fourth Chapter 4, some engineering typical examples are simulated, such as tungsten bar broach projectile impacted onto sand land, tungsten and steel armour-piercing projectile impacted onto thin steel plate and spacecraft whipple shield under hypervelocity impact. The influences of many factors including material, shape, velocity and impact angle are investigated. Some good results are obtained.In the fifth Chapter, the SPH code is used to simulate the Plasticine, paraffine and steel projectile-plate impacting to evaluate the comparability rule on hypervelocity impact. It shows that the comparability rule is accurate and feasible.The concluding remarks of the thesis are given in the last chapter, some shortages about this paper are also pointed out, and some directions about the future research are also proposed as well.