Meshless Sph Method In The Plate Impact Problem Of Numerical Simulation And Application Of Research

Smoothed Particle Hydrodynamics (SPH) is a pure gridless Lagrangian technique which is appealing as a new numerical method used to solve the problems with high deformation. The merits of SPH are: (1) only nodal data are necessary; (2) back- ground grid does not be needed and so the severe problems always associated with mesh distortion in Lagrangian calculation can be avoided; (3) to implement is convenient, etc.Firstly, the basic theory of SPH is introduced in the paper. The concept of kernel approximation is summarized and SPH discrete equations are derived from the hydrodynamic conservation equations. Discussion covers some relative problems such as smoothing function, artificial viscosity, constitutive relations, equation of state, smoothing length choosing and methods of particle search.Secondly, numerical accuracy and stabilities are investigated. Three different numerical iterative algorithms are developed and the accuracy and stabilities of them are compared. Tension and compression instabilities are studied and effects of Conservative Smoothing Approach and artificial viscosity on stabilities are discussed. Based on Taylor series expansion, Modified SPH (MSPH) method is proposed. The discrete forms of the function and its first derivative estimations of the kernel function are deduced in both one and two dimensional space. The results show that MSPH can improve the numerical accuracy effectively, especially at the points near the boundary of a domain in two dimensional cases.Finally, the plastic program is proved to be correct and efficient by Taylor impact. In addition, numerical simulation for impact of bullet on airplane skin is carried out. The diameter and the depth of the deformation region and the residual velocity of the bullet are analyzed to show accordance with experimental results for high velocity impact. In the calculation, the Johnson-Cook constitutive and Mie-Gruneisen equation of state are adopted to develop the method. Three numerical examples for hypervelocity impact are carried out and the results show that SPH is efficient for...