Quick Prediction Method Of Oblique Penetration Trajectory

Oblique penetration is an inevitable motion state when a projectile attacks targets. For non-normal impact, the angle between the target normal and the trajectory,β, is called the oblique angle, and the yaw angleαis defined as that from the projectile centerline to the velocity vector, and that between the projectile axis and the target normal,θ, is the trajectory angle (or impact angle).Normal impact demands that the compressive resisting stress which is always normal to the projectile surface is of axial symmetry with the projectile axis, while it is unsymmetrical for the oblique penetration. The theory and analysis for normal impact can't be applied in the condition of oblique penetration directly. So it is greatly necessary to build up a special theory carrying on oblique penetration studies. The research on oblique penetration not only reinforces the knowledge about law of non-normal impact, but also provides a reference for designing and evaluating penetration properties of a projectile and enhances attacking ability of a weapon system.In this paper, the projectile and target are separately considered to investigate the problem that a rigid projectile non-normally penetrates into a half infinite target. The response of the target is approximated by an analytical forcing function which eliminates the need for discretizing the target as well as the need for a complex contact algorithm. Thus, this methodology substantially reduces the computing time and memory requirements.Based on the method of projectile and target separation, considering the free surface effect and the process of separation and reattachment between the projectile and target, we program a code to calculate the oblique penetration trajectory. What's more, the problems that rigid projectiles non-normally penetrate into half infinite limestone targets and 6061-T6511aluminium target are numerically investigated. And some knowing about oblique penetration have been acquired from the studies.Compared with the actual numerical simulation widely used to calculate the oblique penetration trajectory, the analytical method in this text has the advantages of more clear physical concept and less time spent and especially the more significance for quick decision-making in the time of war.