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Affiliation
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Tsinghua University, State Key Laboratory of Automotive Safety and Energy, Department of Automotive Engineering , Tsinghua University , Beijing , China , Email: zhouqing@tsinghua.edu.cn. |
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Abstract
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OBJECTIVE: Pedestrian lower extremity represents the most frequently injured body region in car-to-pedestrian accidents. The European Directive concerning pedestrian safety was established in 2003 for evaluating pedestrian protection performance of car models. However, design changes have not been quantified ever since. The goal of this study was to investigate front-end profiles of representative passenger car models and the potential influence on pedestrian lower extremity injury risk.
METHODS: The front-end styling of sedan and SUV (Sport Utility Vehicle) released from 2008 to 2011 was characterized by the geometrical parameters related to pedestrian safety and was compared to the representative car models before 2003. Influence of geometrical design change on the resultant risk of injury to pedestrian lower extremity, i.e., knee ligament rupture and long bone fracture, was estimated by a previously developed assessment tool assuming identical structural stiffness. Based on response surface generated from simulation results of a human body model (HBM), the tool provided kinematic and kinetic responses of pedestrian lower extremity resulted from a given car's front-end design.
RESULTS: Newer passenger cars exhibited more "flat" front-end design. The median value of the sedan models provided 87.5 mm less bottom depth, and the SUV models exhibited 94.7 mm less bottom depth. In the lateral impact configuration similar to that in the regulatory test methods, these geometrical changes tend to reduce the injury risk of human knee ligament rupture by 36.6% and 39.6% based on computational approximation. The geometrical changes didn't influence the long bone fracture risk significantly.
CONCLUSIONS: The present study reviewed the geometrical changes of car front-end along with the regulatory concern on pedestrian safety. A preliminary quantitative benefit of the lower extremity injury reduction was estimated based on these geometrical features. Towards a comprehensive understanding of the role that car designs play in pedestrian protection, further investigation is recommended on the structural changes and inclusion of more accident scenarios.
Language: en |