Ballistic Factors of Behind Helmet Blunt Trauma Skull Fracture

Abstract

Ballistic helmets that defeat the threat can still cause head injuries by striking the head with its backface deformation (BFD). In this study the relationship between kinetic energy (KE), helmet backface response and skull fracture severity in protected post-mortem human subjects (PMHS) and swine was explored. Each surrogate was instrumented with force sensors attached to the skull, fitted with a ballistic helmet and shot. Computed tomography (CT) scans of the post-shot helmet deformation were used to quantify the static BFD depth. When investigating the different fracture severity groups, there were no significant differences in the static BFD depths between severity groups, but KE and BFD velocities were able to distinguish between fracture severity groups. The KE of the incoming round was related to the static BFD depth and BFD velocity, where each increased with increasing KE. This study demonstrates that dynamic metrics of the helmet’s backface response are better predictors of injury than the metrics that are currently used.