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An Investigation of Force Characteristics of Various Vehicle Roof Shapes in Jordan Rollover Tests using Simulations Open Access

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Vehicle rollovers are a rare crash event on the roads in the United States, however 10% of all fatalities are caused by rollovers. The FMVSS 216 test is the only established standardized test for evaluation of roof strength currently used by the National Highway Traffic Safety Administration (NHTSA). It is criticized as not rating the safety of every type of vehicle properly. Especially box-shaped vehicles, such as the Scion xB, attract attention in test results with a high rating and real world crashes with poor performance. A lot of research has been conducted on specific vehicles and led to suggestions for more realistic test conditions. With the vehicle roofs being shaped very differently across the fleet, these conditions presumably do not apply to all of them.A dynamic rollover test device, the Jordan Rollover System, was developed by researchers to allow repeatable testing under real rollover conditions. The test device records some forces in the roadbed, but not for all three force components. Therefore, it is impossible to state where the impacting forces during a rollover are directed and what their magnitude is.The direction of the forces might be a useful insight for adjusting the configuration of the FMVSS 216 test.Therefore, in this research approach LS-DYNA simulations under similar conditions to a Jordan Rollover test were conducted and the forces on the roadbed in all three directions were recorded. Since there are only a few Finite Element models of vehicles available, and none of a box-shaped car, the roof shape had to be modeled in a different way. The roof was removed and replaced by a simple tubular cage structure of different shapes and angles.It was shown that it is generally possible to model the behavior of a 2003 Ford Explorer roof in static FMVSS 216 testing and dynamic Jordan Rollover testing with a cage. The forces of four additional roof shapes were simulated and analyzed in several different ways. The results are presented as the trend of the three components of the resulting force on the roadbed, as a visual vector in a 3D-coordinate system and as corresponding angles in the rotating vehicle coordinate system.The results provide researchers with information that was not previously available. A direct recommendation for a more accurate roof strength assessment test based on this study only was not possible, and also not the objective of the study.

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