Preliminary Investigation of Skull Fracture Patterns Using an Impactor Representative of Helmet Back-Face Deformation.

Military combat helmets protect the wearer from a variety of battlefield threats, including projectiles. Helmet back-face deformation (BFD) is the result of the helmet defeating a projectile and deforming inward. Back-face deformation can result in localized blunt impacts to the head. A method was developed to investigate skull injury due to BFD behind-armor blunt trauma. A representative impactor was designed from the BFD profiles of modern combat helmets subjected to ballistic impacts. Three post-mortem human subject head specimens were each impacted using the representative impactor at three anatomical regions (frontal bone, right/left temporo-parietal regions) using a pneumatic projectile launcher. Thirty-six impacts were conducted at energy levels between 5 J and 25 J. Fractures were detected in two specimens. Two of the specimens experienced temporo-parietal fractures while the third specimen experienced no fractures. Biomechanical metrics, including impactor acceleration, were obtained for all tests. The work presented herein describes initial research utilizing a test method enabling the collection of dynamic exposure and biomechanical response data for the skull at the BFD-head interface.