A mathematical breakable leg model was developed and implemented into the pedestrian lower extremity model. The leg model consists of two rigid-body elements connected by a "fracturable joint". The moment-deformation characteristics of the "fracturable joint" are described by the user subroutines, which were prepared and added to the MADYMO three-dimensional program system. The input data for the "fracturable joint" model originate from available biological specimen tests. Computer simulations of car-pedestrian impact with this modified pedestrian model were conducted at a speed of 31 km/h in four different configurations, and compared with previously performed human leg specimen tests. Different types of bumper compliance and bumper levels were simulated. The bumper force, the accelerations, the condyle contact forces and the ligament strains were calculated during simulations. The results showed that the modified model gave a higher biofidelity than did the previous model with the undeformable representation of the leg segments. The calculated parameters such as bumper forces and accelerations corresponded with the measured parameters in tests. The impact response of the lower extremity could be well predicted by the model.
Abstract