Detailed finite element human body models (HBMs), and neck models (NMs) in
particular, have been used to assess response and injury risk with a focus on
frontal, lateral, and rear impact conditions. Although HBMs have successfully
predicted kinematics and the importance of active muscle in simple loading
conditions, they have generally not been assessed for more complex loading
conditions such as non-traditional oblique loading that may be encountered in
future vehicles equipped with automated driving systems.
In this study, a contemporary NM was assessed using oblique human volunteer sled
test data. Average head and first thoracic vertebra kinematics were determined
from the volunteer tests and applied as a boundary condition to the NM. An
open-loop co-contraction muscle activation scheme with four activations times
within reported human limits (50, 75, 100, no activation) was used to
investigate the effect on response and potential for injury risk.
The T1 and head kinematics from 45 oblique impact volunteer tests were analyzed
in five groups according to the peak sled acceleration (4g to 11g), resulting in
mean and standard deviation corridors. The NM ran stably to completion for all
impact cases, demonstrating complex forward excursion of the head, and lateral
bending and axial rotation of the neck under oblique loading. Objective
evaluation of the predicted head kinematics over a range of impact severities
demonstrated fair to good biofidelity (0.65 to 0.77 rating) for the 75 ms
activation time and no tissue damage was identified, in agreement with the
experimental tests. The model correlation was higher for the 50 ms activation
time, suggesting that the volunteer muscle activation times were lower than the
average for the population. The average 75 ms co-contraction activation has
previously provided good results in frontal and lateral impacts and, in the
current study, demonstrated applicability to more complex oblique impact
scenarios that may be encountered in ADS-equipped vehicles.
