Dynamic characterization of kinetic energy non-lethal deformable projectiles using experimental stress-strain curves

Numerical simulations are now widely used for assessing the risk of injury caused by kinetic energy non-lethal projectiles to the human subject. However, the dynamic characterization of these projectiles as well as the human tissues is still challenging. Unlike the non-lethal rigid projectiles of early years that had a high potential of permanent damage, the non-lethal projectiles of new generation are mostly deformable projectiles. Their principal characteristics is the potential of absorbing a substantial part of impact energy by elastic or plastic deformation, reducing consequently the risk of causing severe lesions during the normal use of these projectiles. The 40mm non-lethal projectiles available in the market are generally made of a plastic body and a nose made of rubber or foam material. Unfortunately, there is a wide range of this kind of material presenting by the way different dynamic behavior. One method to characterize such behavior is the use of an optimization process of a parameterized material law. However, this method has its drawbacks. Finding a suitable model is not easy and the process of optimization can be time consuming. Another method is the direct use of stress-strain curves derived from experimental data in a tabulated law. The idea is to derive these stress-strain curves from the experimental impact tests of non-lethal projectiles against a rigid wall at different velocities within the range of their normal use. This method is widely used in commercial FEM-codes like Ls-Dyna for quasistatic tests or at low velocities tests. In this paper, we will investigate how this method can be applied in the non-lethal impact tests where higher impact velocities are expected compared to the crash-test field. Good results have achieved.