Development of an analytical method for ballistic impact of long rod penetrators

Khodadad Vahedi, Louisiana Tech University


An analytical model in terminal ballistic is developed to predict the crater depth of a projectile impacting into a semi-infinite target. A principal objective was to properly account for the strength properties of colliding materials. The entire velocity regime from low to hypervelocity is analyzed. The model developed is based on the assumption of a steady state penetration process, and is used to compare with existing experimental measurements.

The study shows that it is possible to construct a very simple model to accurately predict crater depth for a large number of materials without recourse to the high cost of experimentation. In fact the biggest advantage of this model is simplicity and direct applicability to design process. Penetration mechanics has historically relied heavily on experimental data. This work gives a quick and easy result with sufficient accuracy which may be useful for many applications. An extensive data comparison for tungsten alloy into RHA and steel into steel are included. Several cases of hardened steel into aluminum and aluminum into aluminum are also compared and analyzed.

A parametric study is conducted to determine the influence of the principal penetrator and target variables on penetration depth and hydrodynamic velocity. This includes the study of the effects of such factors as density and ultimate yield strength of the target and penetrator as well as penetrator aspect ratio. It was found that at low velocity impact the effects of all of these parameters are significant, demonstrating that approaches which neglect strength properties cannot adequately describe the penetration process. However, at high velocities the effects of such factors as penetrator aspect ratio as well as the strength characteristics of the impacting materials may be neglected.