Prevention of rear-impact neck injuries remains challenging for safety designers
due to a lack of understanding of the tissue-level response and injury risk.
Soft tissue injuries have been inferred from clinical, cadaveric, and numerical
studies; however, there is a paucity of data for neck muscle injury, commonly
reported as muscle pain. The goal of this study was to investigate the effect of
muscle pre-tension and activation on muscle strain and injury risk resulting
from low-severity rear impacts using a detailed finite element head and neck
model (HNM).
The HNM was extracted from the GHBMC average stature male model and re-postured
to match a volunteer study, with measured T1 kinematics applied as boundary
conditions to the HNM. Three cases were simulated for three impact severities:
the baseline repostured HNM, the HNM including muscle pre-tension, and the HNM
with muscle pre-tension and muscle activation. The head kinematics, vertebral
kinematics, muscle strains, and three neck injury criteria were calculated to
assess injury risk.
The kinematic response of the neck model demonstrated an S-shaped pattern,
followed by extension in the rear impact cases. The maximum kinetics,
kinematics, and muscle strains occurred later in the impact during the extension
phase. The distribution and magnitude of muscle strain depended on muscle
pre-tension and activation, and the largest predicted strains occurred at
locations associated with muscle injury reported in the literature. The HNM with
muscle pre-tension and muscle activation provides a tool to assess rear impact
response and could inform injury mitigation strategies in the future.
