A Computational Analysis of the Airborne Phase of Vehicle Rollover: Occupant Head Excursion and Head-Neck Posture

While previous studies have recognized and demonstrated the upward and outward occupant motion that occurs during the airborne phase of rollover and estimated the resulting head excursion using static and dynamic approaches, the effect of roll rate on restrained occupant head excursion has not been comprehensively evaluated. Moffatt and colleagues recently examined head excursions for near- and far-side occupants resulting from steady-state roll velocities using a laboratory fixture and both Hybrid III anthropomorphic test dummies (ATD) and human volunteers. To expand upon that study, a MADYMO computational model of a rolling airborne vehicle was developed to more thoroughly evaluate the effects of roll rate on occupant kinematics and head excursion. The interior structure of the vehicle used by Moffatt et al. was modeled, and the ATD kinematics observed in that experimental study were used to validate the computational models of the current study. The ATD occupant was modeled with the available TNO Hybrid III ATD multi-body models. In addition to head excursion, this study examines the occupant position at various roll angles and roll rates to map a probable range of occupant positions prior to roof contact. Occupant kinematics are quantified for steady-state roll rates up to 720 deg/s, and demonstrate a nearly linear relation between roll rate and head excursion in the absence of roof contact. This validated MADYMO model will allow for further examination of the injury potential from roof-to-ground contacts based on the orientation of the body, head/neck kinematics, and the “map” of probable relative orientations of the torso, head, and neck at roof-to-ground contact.