Three-dimensional Numerical Model of Free Motion Headform Used in Impact Tests on Vehicle Interior

FMVSS (Federal Motor Vehicle Safety Standard) 201, Standard on Occupant Protection in Interior Impact, requires that the FMH (Free Motion Headform) impact tests result in HIC(d) less than 1000. Especially in the early stage of a vehicle development it is very difficult to conduct the impact tests, so it is necessary to develop a numerical model by which HIC(d) can be predicted. A finite element model for both the FMH and a vehicle can be a good solution, but it needs quite some time and effort to develop such a model. A two-dimensional simple numerical model was developed to predict HIC(d) in the impact tests, but the model does not take into account the impacts where the FMH translates and rotates in three directions. Thus, in this study a new numerical model based on three-dimensional governing equations for the FMH impacting against the interior trim was developed and successfully applied to simulations of the impact tests.