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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.

In this research, a material model was developed that has orthotropic properties with respect to in-plane damage to support finite element strength analysis of components manufactured from a randomly oriented long-fiber thermoplastic composite. This is a composite material with randomly oriented bundles of carbon fibers that are approximately one inch in length. A macroscopic characteristic of the material is isotropic in in-plane terms, but there are differences in the tension and compression damage properties. In consideration of these characteristics, a material model was developed in which the damage evolution rate is correlated with thermodynamic force and stress triaxiality. In-plane damage was assumed to be isotropic with respect to the elements. In order to validate this material model, the results from simulation and three-point bending tests of closed-hat-section beams were compared and found to present a close correlation.