A new neck injury criterion in combined vertical/frontal crashes with head supported mass
This study developed a new neck injury risk function suitable for use in frontal crashes with occupant orientation ranging from predominantly horizontal to predominantly vertical in the occupant anterior-posterior (A/P) direction. In this study, 36 cadaveric head/neck complexes and 6 whole cadavers were tested under impact scenarios with varying total head mounted mass and center of gravity locations. Matched Hybrid III and THOR dummy tests were also performed. The resulting injury criterion is based on a beam model of the lower cervical spine and is expressed as (Equation presented) where F z is the axial compression/tension force, and M y is the A/P flexion moment, both at the C7/T1 intervertebral disc. The derived constant values of F ZC are 5660 N in axial tension and 5430 N in axial compression and M YC is 141 N-m in A/P flexion. These values are comparable to single axis injury tolerance values described in the literature and in existing motor vehicle injury standards for the upper cervical spine (FMVSS-208, 2003). Beam criterion values (BC) of 1.0 correspond to a 50% risk of an AIS ≥ 2 injury in the human cervical spine. The THOR dummy was found to reproduce the kinematics of the cadaver better than did the Hybrid III dummy. However, response curves showed differences between the THOR and the cadaver that were due to anatomy.
