Effect of energy absorbing mechanisms on the blunt thoracic trauma caused by ballistic impacts

military and law enforcement officials have been using kinetic energy non-lethal weapons ranging from rubber bullets to projectiles with foam in situations which do not warrant the usage of lethal force. On many occasions, non-lethal projectiles have caused serious injuries. Therefore, a scholastic study was carried out to see the effect on the injury caused by the projectiles embedded with various energy absorbing mechanisms. Projectile – target interaction (kinetic energy transfer or energy gained by the target and Total energy of the projectile) plays a vital role in understanding the effect of the projectile on the target. Therefore, to evaluate the effect of the energy absorbing mechanisms on the blunt thoracic trauma, target considered should emulate the human thorax as far as the projectile-thorax interaction is concerned. A fully validated FE model of the thoracic surrogate (FE model of the MTHOTA surrogate of the thorax, which is validated with the human response corridors developed by Wayne State University’s researchers) was impacted with a typical foam nosed projectile at a speed of 90 meters per second. A collapsible Aluminum foil attached to the hollow foam nose of the projectile and impact simulations were carried out for different thicknesses of the foil (0.3 mm and 0.5 – 4.0 mm with an increment of 0.5 mm). To nullify the effect of the variation in the mass and also for effective comparison, impact speed was adjusted so that kinetic energy of the projectile remain same for all analyses. For the design of the collapsible mechanisms considered for the study, foil thickness less than 2 mm, though foiled structure got collapsed it didn’t absorb considerable amount of energy. More than 2 mm thickness, foil didn’t collapse properly and whole projectile acted as stiff/solid round and produced more injury. Dynamic force response, dynamic displacement response, effect of the aluminum foil on the thoracic injury in terms of VCmax etc., were presented in this paper