著者

Shoko OIKAWA Yasuhiro MATSUI Asato WAKABAYASHI Sayaka GOMEI Hiromichi NAKADATE Shigeru AOMURA

出版者

一般社団法人 日本機械学会

雑誌

Journal of Biomechanical Science and Engineering (ISSN:18809863)

巻号頁・発行日

pp.15-00613, (Released:2016-04-06)

参考文献数

12

被引用文献数

7

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For cyclist fatalities in 2014 in Japan, the head was the most frequently injured body region. In the present study, the authors analyzed the features of cyclist head injuries in real-world traffic accidents using the data of patients who were taken to the emergency room in Dokkyo Medical University Koshigaya Hospital in Japan, from 2011 to 2013. The results indicated that the percentage of skull fractures was the highest among cyclist head injuries. Assuming that a helmet can prevent head injuries sustained by cyclists in traffic accidents, the effect of wearing a helmet was investigated in impact tests against a vehicle and road pavement. In the tests, the severity of potential head injuries was determined from the Head Injury Criterion (HIC) obtained in an adult pedestrian head-form impactor with and without a helmet. The impact location selected for a vehicle was the A-pillar because the pillar had much higher stiffness than the vehicle bonnet or windshield. It was found that the HIC values for the head-form impactor wearing a helmet were much lower than the HIC values for the head-form impactor not wearing a helmet in both the head-versus-A-pillar impacts and head-versus-pavement impacts. The results suggest that wearing a helmet could reduce the possibility of skull fracture in cyclists.

著者

Shigeru Aomura Hiromichi Nakadate Yuelin Zhang Takahiro Ueno Akiyoshi Nishimura

出版者

The University of Tokushima Faculty of Medicine

雑誌

The Journal of Medical Investigation (ISSN:13431420)

巻号頁・発行日

vol.70, no.1.2, pp.213-220, 2023 (Released:2023-05-11)

参考文献数

21

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In this paper the effectiveness of the support system which predicts the risk of the repetitive brain concussion is studied biomechanically. In the risk prediction system, the accident that caused the concussion is reconstructed by analyzing the game video via multibody dynamics and the resulting brain injury is calculated in detail by the finite element method. In order to calculate the aggravation of the brain injury by the repeated brain concussion, the following two methods are examined. In the first method, the material properties of the part of the brain damaged by the1st impact are changed in the simulation of the 2nd impact. In the second method, each brain damage caused by the repeated impacts is accumulated. The system was applied to the real-life accidents that occurred during Judo and American football games. As a result of the simulations, the aggravation of the brain damage due to repetitive concussion was determined numerically in terms of the maximum strain of the brain and the brain damage rate of the whole brain. The biomechanical process of the collision accidents and the resulting brain damage were reconstructed based on the video and the results are effective to prevent the future repeated concussion accidents. J. Med. Invest. 70 : 213-220, February, 2023

著者

Shoko OIKAWA Hiromichi NAKADATE Yuelin ZHANG Takahiro UENO Shigeru AOMURA Yasuhiro MATSUI

出版者

The Japan Society of Mechanical Engineers

雑誌

Journal of Biomechanical Science and Engineering (ISSN:18809863)

巻号頁・発行日

vol.12, no.4, pp.17-00175, 2017 (Released:2017-09-15)

参考文献数

49

被引用文献数

1

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Severe head injuries can occur in cyclists involved in traffic accidents. In Japan, head injuries accounted for 62% of cyclist fatalities in 2015 (ITARDA, 2016). The purpose of this study is to estimate head injuries for cyclists and quantify the effectiveness of a bicycle helmet by performing finite element (FE) simulations of head impacts against roads. Impacts with and without a helmet over a range of relative head velocities and head impact angles were simulated. A number of possible head injuries were assessed; skull fracture by skull strain, traumatic intracerebral hematoma (ICH) by brain pressure, brain contusion by brain negative-pressure and von Mises stress, and moderate and severe diffuse axonal injuries (DAIs) by von Mises stress. Results showed that without a helmet, the peak values of all metrics exceeded the 50% probability point for head injury in all impacts. The 50% probability points of moderate and severe DAIs were exceeded under impacts of 8.22 m/s at 26.5 degrees and 10.33 m/s at 15.0 degrees for moderate DAI, and 10.33 m/s at 15.0 degrees for severe DAI, without a helmet. All the peak values were reduced when a bicycle helmet was worn, and the largest reduction was found in the skull strain. These results predict that the risks of head injuries due to road impacts may be considerably decreased by helmet use.