Numerical Recreation of Field Cases on a Biofidelic Human FE Model Involving Deformable Less-Lethal Projectiles

International audienceSince the 1970s, there has been an increased interest in the use and development of less lethal kinetic energy (LLKE) projectiles. These weapons are mainly used by law enforcement officers worldwide in cases of riot and crowd control. Even if such projectiles are designed to incapacitate an individual with a low risk of serious injuries, the literature indicates a risk of thorax injuries like rib fractures and lung and heart contusions when a projectile strikes the body. Among published articles discussing the wounding potential of LLKE projectiles, two are particularly well documented describing two field cases involving deformable projectiles (eXact iMpact™ and Flash-Ball®). However, one question remains: how to properly exploit field cases in order to find both injury thresholds and guidelines for the design of LLKE projectiles? Hence, the authors focus their research on the use of numerical tools as the finite element (FE) method to recreate the real impact conditions on a biofidelic human torso FE model. It requires the accurate modeling of the deformable projectiles at dynamic strain rates. To address that issue, the study begins by several ballistic experiments on a rigid wall equipped with a load sensor and a high-speed camera. The impact force measured and high-speed images are directly used in an inverse procedure to optimize model parameters of the concerned projectile to correlate impact experiments and modeling. Finally, this is followed by the impact modeling on the human torso FE model and the identification of model-dependent numerical metrics suitable to predict lung and heart contusions. While efforts need to be pursued, this present research provides an interesting step towards designing effective and reliable LLKE projectiles