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With the increased number of airbags and other advanced restraint systems, the upper and lower extremities are becoming more widely studied to determine the injury potential from these devices. However, little injury tolerance data exist for whole bones. To address this deficiency, a finite element model of a female upper extremity was created from computed tomography scan data. A constant density of 1.86 g/cm3 was assumed with a previously developed transversely isotropic, elastic- plastic material model that incorporates rate effects through a modification to the longitudinal modulus and yield stress. Qualitative simulations were conducted for tension, compression, and torsion along the long axis of the bone and for three-point bending in the anterior-posterior direction. Failure was shown to occur in the area of weakest strength or greatest load.

A simulation model of the Hybrid III lower extremities with the 30 degree dorsiflexion ankle was developed using the CVS/ATB program. The femur and tibia were modeled as a sequence of rigid beams with a hinge and slider at the knee. Special, locked joints were placed in the femur and tibia at the same locations as the load cells in the actual dummy. Constraint forces and moments at these joints can be compared directly to load cell data. The complex geometry of the foot was divided into five segments representing the heel, toe, forefoot, midfoot, and ankle regions. Two foot models were constructed: one barefoot and one with a Lehigh safety shoe. Good agreement was obtained for most parameters when single-leg pendulum tests, and full-body sled tests, were simulated using the new model.

Experimental testing was performed to provide input data for a new, multi-body computer model of the Hybrid III lower extremity, with the 30 degree dorsiflexion ankle. The leg was disassembled into its components to mass, geometric, and inertial properties for each segment. Stiffness and damping coefficients were measured for the hip, leg, foot, and ankle. Joint rotational and translational properties were measured for the knee and ankle. To characterize interactions of the foot with the footwell, flexion and compression tests of the foot were conducted. The lower extremity was segmented at the joint and load cell locations, to permit rigid body dynamics codes to compute the forces at these locations for comparison to test data and for calculation of injury criteria.