The Numerical Simulation Of Projectile Penetrating By SPH Method

High-speed projectile penetrating concreting target is a very complex dynamic problem.Concrete goes through large deformation, high strain rate, high pressure at the process ofpenetrating. Mesh methods such as finite element method will occur mesh distortion, and stopthe calculation in the calculation process. The smoothed particle hydrodynamics method is aform of meshfree lagrangian method. In the SPH method, it is that simulating the model witha series of particles with physical characteristics.This method can avoid mesh distortion, andclearly show the target deformation process. So SPH method has certain advantages inhigh-speed collision.The study status of meshless method were introduced in China and abroad at the firstchapter, including the history and the current development about meshless method. The mainstudy contents and innovation points were listed.The second chapter described the basic theory of SPH method. First, it described thenuclear function approximation process. According to the basic equations of fluid dynamicsSPH discrete expression was derived. It introduced some problems about SPH simulationcalculation, such as smooth function, artificial viscosity, selection of the smooth length,boundary treatment. To master the use of ANSYS/LS_DYNA finite element analysis software,projectile penetration metal target process was numerically simulated on the basis of SPHmethod. The calculation results of SPH method compared with the conventional finiteelement method, discussing the advantages and disadvantages of computational efficiency andaccuracy about two methods in penetrating process.The third chapter described the concrete failure criterion, and simply introduced the threemethods about the penetration problem. And it tried to simulate that the projectile penetratedconcrete target in finite element method, observing the concrete cratering, crushing, andflaking.The fourth chapter built the calculation model of projectile penetrating concrete targetinSPH method and calculated it using LS_DYNA solver. The results show that, SPH methodcan clearly describe the dynamic response behaviors, like collapsing, crushing, splashing andfracture, when the concrete structures were penetrated by projectile. Comparing the impact on the results of different concrete target thickness, penetrating velocity and projectile material isnecessary. The results show that increasing the thickness of the concrete target can effectivelyimprove its penetration capability. It is easily penetrated when the target is thin. Flaking ofback concrete has a large impact on the target. It is disadvantageous for its penetrationcapability. It has large penetration capability when the projectile mass is greater. But thedeformation of the projectile relates to its stiffness, not its mass. And the impact of thepenetrating velocity on penetration capability is larger than the other factors.It is possible to terminate the calculation because of the low computational efficiency ofSPH method. Finite element method coupled with the SPH method in the fifth chapter tosimulate projectile penetrating concrete target. The results of FE-SPH coupling method andSPH method was compared from the aspects of remaining velocity, acceleration, hourglassand total energy. The results show that the FE-SPH coupling method can inherit the advantageof SPH method be coupled under the premise of maintaining accuracy. It also greatlyimproves the computational efficiency, so it can be widely used in high-speed collisionproblems.