Rollover: a methodology for restraint system development

Concern about crash conditions other than frontal and side crashes has accelerated restraint development with respect to rollover events. Previous analysis of rollover field data indicates the high probability of ejection and consequent serious injury or death to unbelted occupants. Partial ejection of belted occupants may also occur. Restraint development has focused on belt technologies and more recently, airbag systems as a method to reduce ejection and injury risk. Effective restraint development for these emerging technologies should consider a combined approach of field injury data analysis, computer simulation of rollover, corresponding validated test data and hardware development techniques. First, crash data was analyzed for identified rollover modes (crash sequences) and injured body regions. This helped to determine possible restraint interventions. Computer models using a combined finite element and multibody approach were created, representing the vehicle and occupant kinematics observed in the rollover modes that were tested. After validating the occupant kinematics, models of an inflatable curtain bag were placed in the baseline model to evaluate the benefits of such a restraint system to both belted and unbelted occupants. Basedon these results, a methodology was developed that allowed the curtain hardware to be developed based on a simple linear impact test. The development parameters include the curtain chamber layout, pressure requirements, and anti-ejection capabilities of the restraint system. Results from all data analysis, modelling and tests will be discussed in this paper. The overall approach has basis in biomechanical tolerance and defines the necessary requirements and subsequent restraint solutions for improved occupant protection in a contemporary crash issue