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Construction of a human pelvis finite element (FE) model with high bio-fidelity is a crucial step for achieving reliable prediction of pelvis injury due to impact loadings. Several human pelvis FE models have previously been developed and improved to investigate pelvis injury mechanisms. However, an important aspect to directly acquire heterogeneous bone material properties from in-vivo computed tomography (CT) information has not been extensively studied. In this research, a new human coxal bone FE model was constructed from in-vivo CT scans of a Japanese adult (age 25, 173 cm, 60 kg). And, heterogeneous material properties such as Young’s modulus and yield stress were deduced from in-vivo CT information of the Japanese coxal bone by using the relationship between CT Hounsfield value and bone density, in an effort to apply the obtained in-vivo material properties for a human pelvis FE model.

Finite element models of the human pelvic part have been developed to analyze the pelvic injury mechanism under lateral loading conditions. However, these models did not simulate the human pelvic joint (sacroiliac joint, pubic symphysis) movements, nor did they consider the strain rate dependency of the pelvic parts. Human materials differ in stiffness according to the loading conditions, particularly the loading speed. The above problems must be solved to obtain a more biofidelic pelvis model. A biofidelic human pelvis finite element model was developed in this research by incorporating several modifications into the H-Model™ developed by NIHON-ESI for commercial use. The H-Model™ also exhibited problems with not simulating the pelvic joint movement and did not consider the strain rate dependency of the pelvic parts. The present model properly applies the pelvic joint movement, and the strain rate dependencies of the pelvic parts were considered.

Evaluation of car front aggressiveness in car-pedestrian accidents is typically done using sub-system tests. Three such tests have been proposed by EEVC/WG17: 1) the legform to bumper test, 2) the upper legform to bonnet leading edge test, and 3) the headform to bonnet top test. These tests were developed to evaluate performance of the car structure at car to pedestrian impact speed of 11.1 m/s (40 km/h), and each of them has its own impactor, impact conditions and injury criteria. However, it has not been determined yet to what extent the EEVC sub-system tests represent real-world pedestrian accidents. Therefore, there are two objectives of this study. First, to clarify the differences between the injury-related responses of full-scale pedestrian dummy and results of sub-system tests obtained under impact conditions simulating car-to-pedestrian accidents. Second, to propose modifications of current sub-system test methods. In the present study, the Polar (Honda R&D) dummy was used.