Biomechanical Response of Military Booted and Unbooted Foot-Ankle-Tibia from Vertical Loading

Area of Science:

• Biomechanics
• Injury Biomechanics
• Anthropomorphic Test Devices (ATDs)

Background:

• The US Army is developing a new ATD to simulate vertical loading during vehicle underbody blasts.
• Existing ATDs require biofidelity data for accurate response simulation.
• Foot-ankle complex response to vertical loading is critical for underbody blast ATD design.

Purpose of the Study:

• To derive biofidelity response corridors for the foot-ankle complex under vertical loading.
• To provide design parameters for a new US Army ATD.
• To establish validation data for human computational models.

Main Methods:

• Conducted non-injurious tests on isolated post mortem human surrogate (PMHS) lower leg specimens.
• Utilized various foot-ankle positions and tested with/without military boots.
• Instrumented specimens with load cells, accelerometers, and strain gages.

Main Results:

• Determined average proximal tibia axial forces at different velocities (e.g., ~2 kN at 4 m/s).
• Measured force and acceleration time-to-peak values (3-5 msec and 2-8 msec, respectively).
• Observed significantly greater off-axis measures (shear, bending) in non-neutral foot postures.

Conclusions:

• Established initial biofidelity response corridors for the ATD lower leg based on PMHS testing.
• Results demonstrate velocity-dependent increases in force responses.
• Data will guide ATD design and serve as validation for computational models.