Analysis of the causes of differences in impact responses between a human lower limb and the flexible pedestrian legform impactor under low and high bumper vehicle impact situations

Isshiki, Takahiro<sup>1</sup>; Konosu, Atsuhiro<sup>1</sup>; Takahashi, Yukou<sup>2</sup>

The current legform impactors cannot adequately simulate the bending load generated on a lower limb of pedestrians due to the lack of representation of the upper body in a collision with a high‐bumper vehicle. It is therefore necessary to develop a new pedestrian legform impact test method applicable for all types of vehicles regardless of the bumper height.

In our previous study, we developed the Simplified Upper Body Part (SUBP) finite element (FE) model, which can represent the upper body by applying it to the human lower limb FE model.

In this study, we attached the SUBP FE model to the flexible pedestrian legform impactor (FlexPLI) FE model then compared it to the SUBP FE model attached to the human lower limb FE model. As a result, the models showed different impact responses. We estimated this was due to the differences between the human lower limb and the FlexPLI. We therefore investigated the main factors of the different impact responses, and clarified the following six improved points to an advanced pedestrian legform impactor to be used for a new pedestrian legform impact test method applicable for all types of vehicles regardless of the bumper height: (1) Mass distribution of the flesh and the long bones, (2) Geometric layout of the ACL and the PCL, (3) Femoral offset, (4) Representation of the ankle joint, (5) Shape of the impact surface of the long bones, (6) Femur bending stiffness.

Keywords: pedestrian protection test method, legform impactor, influences of the upper body, computer simulation

Year

Entry

2009

Konosu A, Issiki T, Takahashi Y. Evaluation of the validity of the tibia fracture assessment using the upper tibia acceleration employed in the TRL legform impactor. In: Proceedings of the 2009 International IRCOBI Conference on the Biomechanics of Impact. September 9-11, 2009; York, UK.251-267.

2007

Issiki T, Konosu A, Tanahashi M. Development of an FE biofidelic flexible pedestrian leg-form impactor (Flex-GT-prototype) model. In: Proceedings of the 20th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 18-21, 2007; Lyon, France.

2006

Kikuchi Y, Takahashi Y, Mori F. Development of a finite element model for a pedestrian pelvis and lower limb. In: Proceedings of the SAE World Congress & Exhibition. April 3-6, 2006; Detroit, MI. Warrendale, PA: Society of Automotive Engineers. SAE 2006-01-0683.

2013

Takahashi Y, Imaizumi I, Asanuma H, Ikeda M. Responses of the flexible legform impactor in car impacts. In: Proceedings of the 2013 International IRCOBI Conference on the Biomechanics of Injury. September 11-13, 2013; Gothenburg, Sweden.777-788.

2005