Theoretical Analysis And Numerical Simulation Of Ogive-Nose Projectiles Penetrating Into Water And Sand Medium

On the background of target characteristics identification of Offshore Weapon's fuze, in this dissertation, the overloadings of Stick-Ogive-Nose projectile penetrating into water and sand medium were studied with theoretical analysis and numerical simulation. The series of approaches are applicable to the analysis of penetration problem for general Ogive-Nose projectiles.In the theoretical analysis, a dimensionless Nose Performance Coefficient A^ is introduced for describing the penetration performance of general Ogive-Nose, which is available for ogival, conical, flat, and truncated nose projectiles. It was validated with the test data that the Forrestal's penetration model modified by coefficient NL is more applicable and effective than the original one, and that doesn't depend on any empirical parameter. And based on the Spherical Cavity Expansion Theory, a resistance equation for sand penetration with general nose shape projectiles. The equation is especially applicable to complicated nose shape projectiles penetrating into soil and sand medium, and it can also be used to rock and concrete penetration with some transformation. A computation code P2G was developed accordingly. And then the overload curve of projectile impacting to water is solved based on the NL and added mass approach, and the overload curve of projectile penetrating into sand is gained with the Forrestal's model modified by NL and the code P2G.In the numerical simulation, employing the nonlinear dynamic analysis software LS-DYNA3D, the water splashing and the sand deformation were simulated with ALE arithmetic and Adaptive Meshing techniques. And the corresponding overloading curve was supplied.The comparison shows that the results of theoretical analysis and numerical simulation are accordant to each ather on the whole. If we can develop more penetration tests, more exact physical and mechanical model will be established, and the theoretical analysis will be more applicable to practical application.Finally, based on the numerical simulation and the code P2G, the effect of stick length to overloading curve is analysed.