Human Volunteer Head-Neck Response in Frontal Flexion: A New Analysis

At the Naval BioDynamics Laboratory (NBDL) in New Orleans a large series of human volunteer experiments has been conducted by Ewing and Thomas [1]* to determine the dynamic head-neck response. From a number of these experiments Wismans et al. [2] determined omni-directional dummy head-neck performance requirements relative to a non-rotated T1 coordinate system (i.e. the head motions incorporate the influence of the thoracic column flexibility). In 1987, the frontal volunteer head-neck response was compared with the response of postmortem human subject (PMHS) experiments [3]. One of the findings was that the volunteer T1 rotations differ significantly from the PMHS T1 rotations which was explained by measurement “errors” in the T1 instrumentation. The present paper is an extension of the previous work [2,3]. A detailed analysis of the high-speed films revealed that the volunteer T1 instrumentation mount was not firmly mounted to the spine. In the present analysis a T1 correction is applied to the experiments used in the previous analyses. A description of the correction methodology will be presented. The objective of the present study is to correct for the errors in the T1 rotations and to develop a set of new performance requirements which are expressed relative to a rotated T1 coordinate system. New requirements will be presented and compared with previous analyses. Additionally, the dynamic response of the Hybrid III dummy neck will be evaluated on the basis of the new performance requirements.