Mechanics of interaction of blast waves on surrogate head: Effect of head orientation

Blast induced Traumatic Brain Injury (bTBI) has emerged as the most significant injury to warfighters in recent conflicts. How blast waves interact with the head and head protection device (helmet), and induce biomechanical loading on the head are not fully understood. This work focuses on the mechanics of blast wave head interactions on a surrogate head for various orientations (front, back, side and 45°) using experiments and numerical models. The role of the orientation of the head on the mechanical load experienced by the head is studied by monitoring pressures on the surface of a surrogate head subjected to planar blast waves. Validated numerical models are further employed to understand the experimental results and to interpret various aspects of flow mechanics (e.g. flow separation, flow reunion) around the head. Our results indicate that geometry of the head and its orientation with respect to the direction of the blast, govern the flow dynamics around the head and this alters the surface pressures experienced by the head. Orientation dependent responses predicted by the experiments and numerical models suggest that direction-specific tolerances are needed in the helmet design, in order to offer multi-directional protection under blast loading conditions.