Risk of rib fractures assessment during kinetic energy projectile impact through experiments and modelling on a human torso FE model
Résumé
The past decade has seen the rapid increase in ballistic impact studies, especially to understand the human body response, as well as to improve protective equipment. Indeed, the literature refers to severe blunt trauma caused by Less-Lethal Kinetic Energy (LLKE) projectiles but also by the body armour deformation called Behind Armour Blunt Trauma (BABT). Various materials have been employed as ballistic testing media such as ballistic gelatin and clay. Among these, a synthetic gel named SEBS is adopted by the French Ministry of the Interior as ballistic testing medium for impact interpretation. Although gel transparency provides a direct impact analysis using high-speed camera and provides information on the dynamic gel wall displacement, macroscopic data do not allow a direct evaluation of the risk of blunt trauma. Hence, the authors focus their research on the use of a biofidelic human torso finite element (FE) model named HUByx for impact modelling. The study of C. Bir about the impact of rigid LLKE projectiles on Post-Mortem Human Subjects' sternum (PMHS) are exploited by reproducing impact conditions on both a gel block and a human torso FE model. This study results in the establishment of a probability of rib fractures as a function of the viscous criterion. On the one hand, these tests are employed to validate the torso model by comparing with biomechanical corridors. On the other hand, it allows the development of a methodology to obtain the risk of skeleton injuries based solely on experimental gel block data. Indeed, a statistical approach based on twelve impact tests is employed to define a suitable transfer function between results from a gel block test and the risk of rib fractures. A perspective of this study would be to apply and extend this strategy to the study of BABT only caused by body armour deformation.