Investigation of Boundary Conditions for Vehicle Rollover Simulations

Rollover crashes constitute almost 30% of occupants deaths in highway crashes, although they account for only 3% of all vehicle accidents. Most of the accidents are single-vehicle collisions (68%) after departing the roadway (63%), and almost half of the occupants involved in such accidents are ejected from the vehicle during rollover accidents. Therefore, a Federal Motor Vehicle Safety Standards (FMVSS) 226 regulation on ejection mitigation has been established. The most commonly used restraint system is a seat belt with a rollover-activated side curtain airbag. Designing effective restraints requires a standardized, repeatable test conditions, which remains a challenge for the rollover scenario, One way to address this challenge is through the use of numerical models that provided repeatability and the ability to investigate a wide range of test conditions. However, simulations of rollover are challenging due to the wide variety of boundary conditions that may result in a rollover, and the long duration of these events (on the order of seconds). Most modeling approaches that involve occupant injury prediction focus on representing physical tests that mimic simplified rollover conditions in roof strength tests. A primary challenge in simulating rollover is that existing numerical models were not constructed for this purpose and often result in instabilities, or require significant modifications to simulate rollover using simple boundary conditions. This paper presents a numerical approach to model dynamic rollover conditions using existing vehicle models without any modification to the vehicle model.