Modeling the Effect of Initial Disturbances when a Bullet Impact in Gelatin

Impact experiments with gelatin targets often lack information on the pitch rate of the bullet at the time of impact. Usually, this boundary condition is also ignored in numerical modelling. To investigate the effect of pitch rate on the bullets behavior in gelatin, a numerical study is performed for various impact angles and pitch rates. To enable this study, a constitutive model describing the hyperelastic, nearly incompressible and viscoelastic behavior of gelatin is implemented in a commercial finite element code. We investigate how the pitch rate and impact angle affects the depth where a full metal jacket bullet starts to tumble in a gelatin target. Results indicate that whilst the impact angle dominates the bulletgelatin interaction, large pitch rates (>150 rad/s) should be included in any analysis. However, in most ballistic experiments the pitch rate is low (<70 rad/s) and its effect can largely be ignored in simulations or analysis.