Response and injury of the human leg for axial impact durations applicable to automotive intrusion and underbody blast environments

<p>Similar lower extremity injuries occur in both military vehicle underbody blast and automotive intrusion events despite the drastic differences in acceleration, velocity, and load duration. Understanding human leg response to variations in load rate and boundary condition is imperative to assessment of injury using anthropomorphic test devices (ATDs). Two axial impact test series were performed using post-mortem human surrogate legs, varying load rates and using ‘fixed’ and translational proximal tibia boundaries. Corridors were developed for a 50th percentile male for five loading rates ranging from 0.3 to 12 kN/ms. Calculated leg stiffness ranged from 700 to 1600 N/mm, and foot and ankle compression at peak force accounted for greater than 75% of lower leg compression. Injuries included calcaneus, talus, pilon, and malleolar fractures. Results indicated a duration-dependence of fracture force, which has major implications for the validity of existing injury criteria and the future design of ATD legs.