Sadayuki Kuwahara

Finite Element Analysis of Pedestrian Lower Extremity Injuries in Car-to-Pedestrian Impacts

This paper is from the SAE World Congress & Exhibition, held in April 2007 in Detroit, Michigan, USA. Part of the Pedestrian Safety session, this paper describes a study that used a human finite element (FE) model to better understand the dynamics of an impact between a car and a pedestrian. As a way to understand the mechanisms of and prevent lower extremity injuries to a pedestrian when struck by a car, researchers must determine the loadings from car front structures on the lower extremities of the body. The authors introduced a bending moment diagram and a stress diagram of the tibia to examine the effects of loading from car structures. Certain positions of the lower absorber reduced the tibia fracture and knee injury risks. The authors also conducted an FE analysis of a legform impact test using the TRL legform impactor. A relationship was found between the injury criteria of the TRL legform impactor and the human FE model. High acceleration of the TRL legform impactor corresponded to the tibia fracture or MCL rupture of the human FE model.

Analysis of loading of lower extremities based on bending moment in car-to-pedestrian collisions

In this study, simulations of car-to-pedestrian collisions were conducted using multibody pedestrian models and a finite-element (FE) car model in order to examine the loadings on the lower extremity of the pedestrian. Bending moment diagrams were plotted versus time for the tibia, knee and femur; and the loadings on the lower extremities were evaluated using time-series comparisons. An analysis using a human FE pedestrian model also was conducted. The bending moment of the lower extremity was found to be comparable between the multibody and FE models. Car-to-pedestrian collisions were also simulated for various sizes of pedestrians. The bending moments were larger as the pedestrian size was larger, whereas the curve shape of the bending moment diagrams was similar for all sizes of pedestrians. It was shown that the bending moment diagrams using the multibody pedestrian models were useful for investigating the loading on the lower extremities for various sizes of pedestrians.