Experimental Investigation of the Ballistic Response of Head Surrogate Against Fragment Simulating Projectiles

Background Penetrating combat injuries by fragments are of concern during tactical warfare. The fragments generated from the explosive devices can cause lethal penetration in various organs, including the head. The response of the head against fragment impact is unknown. Objective To experimentally investigate the ballistic response of an open-shape head surrogate model against fragment impact. We hypothesize that the response of the head surrogate to the impact of small fragments is different than that of larger projectiles. The ballistic response of the head surrogate was evaluated in terms of ballistic limit velocities (V 50 ), energies (E 50 ), energy densities (E 50 /A) required for the penetration, and associated failure mechanisms in various layers of the head surrogate. Methods The head surrogate was prepared by stacking rectangle cross-sectioned skin, skull, and brain simulants. Chisel-nosed fragment simulating projectiles (FSPs) of 1.10-g and 2.79-g were impacted on the head surrogate using a pneumatic gas gun setup. Results V 50 and E 50 /A of the 2.79-g FSP were lower by ~ 50% than the 1.10-g FSP. The skin simulant failed by the combination of shearing and elastic hole enlargement. The skull simulant failed by a conoid fracture. In penetration cases, the FSP broke the fractured conoid of the skull simulant in smaller pieces and penetrated into the brain simulant. Interestingly, for the cases of non-penetration into the brain simulant, the brain simulant was damaged due to the moving conoid of the skull simulant. Conclusion The results demonstrated that V 50 and E 50 /A were influenced by the size of the FSP. For the investigated fragments, 15–25 J of energy was sufficient to cause various degrees of penetration into the brain simulant. All three layers of the head surrogate failed by distinguished mechanisms.