Development Of A Certification Procedure For Numerical Pedestrian Models

In the Euro NCAP testing of deployable pedestrian protection systems (i.e. active bonnets and airbags), head impact time (HIT), wrap around distance and bonnet deflection due to body loading are assessed by means of simulations with numerical pedestrian models. The aim of this study was to define requirements for numerical pedestrian models and simulation setups to ensure comparable performance of models and simulation results. These requirements were summarized in a certification procedure which focuses on the pedestrian’s kinematics that are important for the Euro NCAP assessment. Twelve different institutions (academia and industry) applied a harmonised pedestrian simulation protocol, which was established within a previous study. Numerical pedestrian models in the stature of the 50th percentile male (all applicable for the assessment of deployable systems until 2017) were impacted with four differently shaped generic vehicle models at three different collision speeds according to the protocol. Trajectories, contact forces and HITs were evaluated. Finally, 18 full data sets including the 12 load cases were available covering different Human Body Models and Humanoid Multibody Models in four different FE codes. Reference values, corridors and tolerances for the certification procedure were derived, based on identified consistent results. Comparable behaviour was observed for the majority of pedestrian models. However, a small number of simulations showed clearly outlying behaviour in terms of HITs, trajectories and contact forces. The consistent models were within a range of +3.5% and -7% throughout all load cases. Corridors for the z- and x- trajectories as a function of time were developed for the head centre of gravity, T12 and the centre of acetabuli for each load case. Furthermore, corridors for the contact forces between pedestrian model and generic vehicle model were established. The developed certification procedure ensures that a specific pedestrian model within a specific environment, solver version and specific simulation settings gives comparable kinematic results relevant for the assessment of deployable systems. Inconsistent pedestrian models, incompatibilities with control settings and user errors can be identified and sorted out. The procedure was implemented in the Euro NCAP Technical Bulletin 24 and has been in force since January 2018.