Numerical Simulation Of Projectile Penetrating Concrete By SPH Method

Penetration of high-speed projectile to a concrete target is a very complicated dynamical problem. In the penetration process, concrete experiences large deformation, high strain rate and high pressure, so that mesh distortion occurs in the finite element method and other mesh methods in the calculation process, thereby resulting in the problems that the calculation is slow or even aborted. However, the method of Smoothed Particle Hydrodynamics (SPH) is a particle method without meshed of the Lagrange form. In the SPH method, the state of the system is described by a series of particles without meshing, thereby avoiding the occurrence of distorted and aberrant meshes; and the SPH method has a significant advantage in solving large-deformation problems.Firstly, the paper introduces the principal theory of the SPH method first, and then presents a proximate idea of kernel function. The discrietization expression of SPH is deduced according to the fundamental equations of hydrokinetics; and some related problems of carrying out analog computation by utilizing the SPH method is introduced, including smooth kernel function, artificial viscosity, constitutive relation, state equation and selection of the smooth length.Secondly, the composition of concrete materials and the mechanical property thereof are described; and a long-rod projectile is taken for example to discuss the mechanical response and the failure mode that the concrete materials present when penetrated. The influence factors of penetration response to a target, as well as micro crack, damage and such characteristics as strain softening and the like are described. Moreover, the dynamic process that a projectile penetrates a concrete target is introduced briefly.Finally, in the basis of the discussion above, a computational model that the projectile penetrates the concrete target based on the SPH method is established; and the established computational model is solved by utilizing the SPH algorithmic procedure in an ANSYS/AUTODYN finite element analysis software. The penetration processes of projectiles with different initial velocities to the concrete target are simulated; and the fact that how the concrete target is damaged after penetrated by the projectiles with different initial velocities is studied. Compared the numerical simulation result with the experimental result in the references, it shows that as the initial velocity of the projectile increases, the result obtained by numerical simulation is more and more closer to the experimental result. According to the conclusion above, the main factor which influences the precision of the numerical simulation result is analyzed; besides, numerical simulation study on the influence of the number of the SPH particles to the precision of the simulation result is carried out to discuss the degree of closeness of the numerical simulation result and the experimental result under the circumstance of different numbers of particles. The result shows that as the number of the particles increases, the numerical simulation result is more closer to the experimental result as well.The result can provide references for the problems of high-speed projectile penetration concrete projects.