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FMVSS 226 will become effective on September 1, 2013 with the purpose of mitigating occupant ejections through the vehicle side windows. In order to use deployable counter measures to mitigate ejection, vehicle rollover tests are needed to design deployment algorithms for rollover condtions. Vehicle manufacturers have to define their own test procedures, because FMVSS 226 does not define any rollover test methods. The soil trip rollover test is a vehicle rollover test method in which a vehicle is propelled into a soil pool to measure its rollover characteristics. Some of difficulties in soil trip rollover tests include proper maintenance of soil, for example, under fluctuating humidity and homogeneity of soil in the pool, so as to ensure stable repeatability of test results. Protection of onboard measurement equipment in a test vehicle from soil incursion when the vehicle rolls over can also be a challenge.

This paper presents a vehicle dynamic simulation using a finite element method for performing more accurate simulations under extreme operating conditions with large tire deformation. A new hourglass control scheme implemented in an explicit finite element analysis code LS-DYNA(1) is used to stabilize tire deformation. The tires and suspension systems are fully modeled using finite elements and are connected to a rigid body that represents the whole vehicle body as well as the engine, drive train system and all other interior parts. This model is used to perform cornering and braking behavior simulations and the results are compared with experimental data. In the cornering behavior simulation, the calculated lateral acceleration and yaw rate at the vehicle's center of gravity agree well with the experimental results. Their nonlinear behavior is also well expressed.