Paratroopers have been among those in the Army at the highest risk of serious injuries. Majority of these injuries is to the lower extremity and is caused by excessive impact forces. An integrated approach including laboratory tests and numerical simulation was applied to investigate the mechanical behavior of paratroopers during the parachute landing fall (PLF) in order to reduce related injuries. Laboratory PLF tests were conducted to evaluate impact forces, joint forces and moments, kinematics data, and muscle activity. The tests will not only help us better understand injury mechanisms but also provide data for model validation. A finite element model of a paratrooper consisting of rigid ellipsoids and joints was generated for PLF simulation. Particular attention was paid to the modeling of the ankle/foot complex. The passive and active components of the joint properties in the model are separately represented to better simulate muscle action. The pre-programmed ground roll in the parachute landing fall was simulated by a perturbation approach. The predicted landing events and impact forces of the model are in agreement with the data collected from the tests. The model can be used to assess the effectiveness of an innovative ankle brace design and other lower extremities injury related research.
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