Simulation Fidelity Improvement of H350 Lower Tibia Indices 2015-01-0578

Finite element dummy models have been more and more widely applied in virtual development of occupant protection systems across the automotive industry due to their predictive capabilities. H350 dyna dummy model [1] is a finite element representation of the Hybrid III male dummy [2], which is designed to represent the average of the United States adult male population. Lower extremity injuries continue to occur in front crash accidents despite increasing improvement of vehicle crashworthiness and occupant restraint system. It is therefore desirable to predict lower tibia injury numbers in front occupant simulations. Though lower tibia loading/index predictions are not studied as much as the FMVSS 208 regulated injury numbers, the tibia indices are injury criteria that need to be assessed during IIHS and Euro NCAP frontal offset occupant simulations. However during front crash simulations, it is very difficult to achieve good correlations or predictions of lower tibia loadings. A common issue is that the simulations often over-predict lower tibia loading (forces and/or moments) and in turn generate unrealistically higher tibia indices. For this reason, safety CAE engineers are not yet confident in presenting correlations or predictions of the lower tibia loadings/indices. This paper employs Pugh Concept Selection to study the effects of dummy foot location and carpet to sled buck floor interaction on the lower tibia loading/index response. Based on the understanding gained, improvements in the simulation fidelity of lower tibia indices were achieved. Additionally, these findings demonstrate that overall dummy performance is affected by the lower tibia index differences.