Biomechanical Simulation and Animation of Vehicle Occupant Kinematics for Restrained and Unrestrained Conditions in Rollover Accidents

Current transportation safety interests involving the use of restraints in school buses, coupled with litigation claims arising from injuries to unrestrained occupants of school buses involved in rollovers, resulted in a study aimed at: understanding the biomechanical response and injury causing factors associated with unrestrained students involved in an actual school bus roll-over accident; and, comparing the unrestrained response condition to the hypothetical response if the students were lap belt restrained in the same rollover. A numerical occupant simulation computer code was used to input vehicle rollover motion to both belted and unbelted occupants. The unrestrained case theoretically duplicated the injury producing conditions that led to serious head and neck injury in certain students. The hypothetical case of lap belt restrained students demonstrated that the serious injury producing conditions could have been eliminated had lap belts been available and used during the actual roll-over accident. To more clearly demonstrate graphically the occupant kinematics for both conditions, the numerical computer analysis data is displayed as a series of orthographic images of interlinked ellipsoids. This data is then scanned into a 3-D graphics code with more realistic human models to allow real-time and slow motion viewing of the occupant response from both on board and off board view stations. The low cost and limited time needed to perform the analysis are less than experimental costs and suggest the analysis method can provide valuable insight into the benefits of utilizing restraints to prevent ejection and injury in vehicle rollover.