On Predicting Lower Leg Injuries for the EuroNCAP Front Crash

Validation of occupant lower leg injury performance is a difficult procedure due to the complex interaction between occupant and vehicle structure. As a starting point, a carefully validated structural model is crucial to ensure the accurate load of the occupant model in terms of acceleration and applied forces. However, even after a tedious validation of structural performance and occupant environment, the calculated tibia values might still deviate from the test results. Some of these deviations may be caused by restrictions in the occupant model fidelity. This becomes evident in an offset-crash simulation (EuroNCAP), since the complex force behaviour (x, y, and z- components) do not seem to be reproduced by existing occupant models to 100% satisfaction. Especially the dummy joint representation for the ankle, knee and pelvis might cause deviations between the occupant model and the test. Modifications of joint parameters were done to demonstrate a significant potential in the improvement of the fidelity of the occupant model and to bring the tibia injury criteria closer to the test results. This paper presents a detailed numerical analysis to point out the discussed difficulties and proposes possible approaches for a more realistic prediction of tibia values in the case of the EuroNCAP front crash. The proposed changes in this paper will not replace the need to permanently improve the standard FE dummies, but should be seen as a part of the discussion in order to improve the fidelity of the standard dummies in the future.