VELOCITY DECAY IN BALLISTIC GELATIN USING EXPERIMENTAL AND COMPUTATIONAL ANALYSIS

Abstract

Ballistic gelatin has long been used as simulant for the evaluation of small caliber threats against soft targets. The use of gelatin as a soft target simulant date back to the 1960’s and has been an area of active research since. As a substitute for living tissue ballistic gelatin allows for a reproducible, ethical, and cost efficient medium for obtaining experimental data. Experiments and numerical studies carried out at Picatinny Arsenal, US Army, Armaments Center, New Jersey, have shown that while good agreement can be achieved with traditional material models it is usually only valid over a range of impact velocities and projectile weights. This study was also limited by the limited experimental data points obtained. Follow-up experiments were conducted involving a 15.8 grain sphere impacting gelatin at velocities ranging from 2000 ft/s to 500 ft/s. The use of high speed cameras and tracking software during the penetration event allowed for the capture of the velocity decay curve for each experiment. Finite Element impact simulations were then created using the Finite Element code IMPETUS AFEA. The use of the surface SPH method is explored in this study. Previous numerical experiments have shown advantages to this approach, such as eliminating advection errors due to Eulerian material boundaries. The ballistic response of the simulations was compared to test data to calibrate material properties. Data from previous studies suggests that ballistic gelatin shows a strong strain rate dependency. Due to this and the limitation shown from previous research, this study will examine the need of rate-dependent material models for the response of the gelatin. The results from experimental tests are compared with the numerical models to determine the best approach to capturing the ballistic response of gelatin over a wide range of impact velocities.