Evaluation of Blast Mitigation Capability of Advanced Combat Helmet by Finite Element Modeling

Primary blast wave induced traumatic brain injury and posttraumatic stress disorders have been observed in great number among military personnel in the recent Iraq and Afghanistan wars. Although combat helmets provide good protection against blunt/ballistic type threats, the current issue with military helmets is protection concerning the threats from primary blast wave. This study focused on investigating how combat helmets influence the blast- induced biomechanical loads in the human brain. Multi-Material Arbitrary Lagrangian Eulerian method was applied to simulate the wave propagation in the shock tube, the interaction of the shock wave with the human head, and the subsequent blast overpressure transformation through the head. The finite element model (FE) of Wayne State University shock wave generator (WSUSG) was developed and validated against experimentally measured side-on pressure time histories within the tube. Validated 3-D FE models of the human head and Advanced Combat Helmet (ACH) reported previously were used to predict the internal brain responses and assess the performance of the helmet in mitigating shock wave of various severities generated by WSUSG. Effectiveness of helmet with respect to various head orientations to oncoming shock waves was also evaluated. Biomechanical response parameters including the peak brain pressures and strains at various regions of the brain were calculated and compared between the heads with and without helmet. Wearing ACH was found to mitigate the intracranial pressures up to 33% at given blast loading conditions. The peak brain strain was reduced by 13-40% due to the use of helmet. In generally, ACH exhibited increased protective performance as the shock intensity increased. The current ACH helmet design offered superior protection to the brain in sideways blast than that in forward blast loading condition of same severity.