Exposure of a spherical human skull substitute to free-field blast conditions

Abstract

On the battlefield, soldiers may be injured by the detonation of explosive charges, particularly to the head. Several injury mechanisms have been proposed in the literature to explain the observed brain lesions, and numerous experiments, such as post-mortem studies, have been carried out to investigate those hypotheses. In the current study, a new skull substitute has been developed and its mechanical behaviour has been evaluated under free-field blast conditions. Instrumentation included accelerometers, strain gauges, and pressure sensors mounted in multiple positions. The substitute was embedded on a rigid mount and subjected to the detonation of 21 explosive charges. The proposed experimental campaign included seven free-field scenarios with incident pressures ranging from 75 to 200 kPa and two blast durations of 1.2 ms and 2.0 ms. The time analysis of signals revealed an “ipsi-contralateral” effect for internal pressures, i.e., an overpressure at the ipsilateral site concomitant to a depressure at the contralateral site. A slight underestimation of the first peaks versus incident pressures was also observed when compared with the literature on post-mortem human subjects. For shell strains, an overestimation of the maximum values and the first peak values versus incident pressures was attested compared to the bibliographic data. According to the current findings, the newly designed skull substitute produces results in line with post-mortem human subjects in terms of first peak strain and peak internal pressure trends. The described methodology could be applied to develop new head substitutes and, in the future, investigate injury mechanisms.