Investigation of Influence of Impact Condition on Whole Body Trajectory of Powered Two Wheeler Driver in Collision to Car Side

動画引用元論文

Investigation of Influence of Impact Condition on Whole Body Trajectory of Powered Two Wheeler Driver in Collision to Car Side

著　者
Toshiyuki Yanaoka, Yutaka Aikyo, Yasuaki Gunji
収　録
2025 International Journal of Automotive Engineering
発　行
June 26, 2025
要　旨
In order to accurately predict the impact condition of each body region to the car surface from the initial impact condition between the car and powered two wheeler, the influence of the initial impact condition on the trajectory of the driver of the powered two wheeler was investigated by using FE collision simulations. Impact angle, and velocities of the both car and powered two wheeler were used as the parameter to define the initial impact condition. The trajectories of the Head, T1, Upper Thorax and Pelvis and velocities of these body parts were obtained from the time history of the coordinate data of the FE collision simulations. The trajectories of each body region showed following tendency: 1) The influence of impact angle, car velocity and powered two wheeler velocity on the trajectories became larger as the initial location of body parts was lower. Specifically, the Head moves approximately straight along with initial velocity direction until the Head impacts to the car. 2) Decrease of resultant velocity of each part of the body becomes small when the impact angle is different from perpendicular. The findings from this study can be used as the basic knowledge for the powered two wheeler driver’s trajectories to accurately predict the impact condition of each body region to the car surface from the initial impact condition between the car and powered two wheeler.

Speaker

柳岡 寿幸
柳岡 寿幸 / Toshiyuki Yanaoka

その他 執筆論文（共著含む）

頭部FE モデルを用いた衝撃入力に対する脳内応答に影響を及ぼす加齢因子の検討

著　者
柳岡 寿幸、独古 泰裕
収　録
自動車技術会論文集, 2013, 44巻, 6号, p. 1421-1426
発　行
2013年
要　旨
国内の交通事故による死者低減のためには，高齢者の脳傷害基準作成が重要な課題の一つであるが，ほとんど研究がなされていないのが現状である．本論文では，高齢者脳傷害メカニズムを解明するための頭部有限要素モデルに反映すべき特徴を抽出することを目的とし，頭部有限要素モデルを用いたパラメータスタディを行った．

歩行者事故再現可能な簡易車両モデルの検討

著　者
浅沼 宏幸、池田 美和子、柳岡 寿幸、高橋 裕公
収　録
自動車技術会論文集 2013, 44巻, 6号, p. 1427-1432
発　行
2013年
要　旨
本研究では，さまざまな体格の歩行者と車両との衝突を適切に再現し，車体特性の影響も検討可能な車両モデルを構築するため，ボンネットを複数の剛体パネルで分割し，部位別の荷重-変位特性を反映した簡易モデルを検討した．そして，実機フルモデルおよびボンネットを分割しないモデルとの比較により有用性を検証した。

年齢別人体FE モデルの側面衝撃に対する検証

著　者
独古 泰裕、柳岡 寿幸、大橋 一樹
収　録
自動車技術会論文集 2013, 44巻, 6号, p.1433-1438
発　行
2013年
要　旨
近年対応の必要性が高まっている，交通事故に対する高齢者保護のために，著者らは成人および高齢者の挙動および傷害評価が可能な人体FEモデルの開発を行ってきた．これまでに骨の単体，部分衝撃，正面衝突時の全身挙動の予測精度検証を行ってきたが，今回は側面からの衝撃に対する応答予測の検証結果を発表する。

年代別人体頭部有限要素モデルを用いた 加齢による脳内応答の変化に関する研究

著　者
柳岡 寿幸、独古 泰裕
収　録
自動車技術会論文集, 2014, 45巻, 6号, p. 1111-1116
発　行
2014年
要　旨
国内の交通事故による死者低減のためには，高齢者の脳傷害基準作成が重要な課題の一つであるが，ほとんど研究がなされていない．本論文では，形状及び物性の年代差を反映した頭部有限要素モデルを用いて同一衝撃条件における脳内応答の変化について調べ，高齢者の傷害の受けやすさに影響する要因について検討した。

Investigation of the Effect of the Height Alignment on the Validity of the Scaled Whole Body Trajectories in Car-to-pedestrian Collisions

著　者
T Yanaoka, K Torikai, Y Takahashi
収　録
International Journal of Automotive Engineering, 2016, Volume 7, Issue 1, Pages 45-51
発　行
2016年
要　旨
In order to identify the height alignment with a standard-sized pedestrian that best estimates the whole body trajectories by scaling those of a pedestrian in a different size, car-to-pedestrian collision simulations were conducted using five production car models in the small sedan category, human FE models in three sizes and five aligned points with the standard-sized pedestrian. The trajectories from the simulations were scaled using the distance between the aligned point and the measurement point of the trajectory. The results showed that aligning with the knee-joint height provided the best estimation of the trajectories in the small sedan category.

Prediction of probability of fatality due to brain injury in traffic accidents

著　者
Y Takahashi, T Yanaoka, H Sugaya, AV Basilio, P Xu, G Ateshian, B Morrison
収　録
Traffic Inj Prev, 20(sup1):S27, https://doi.org/10.1080/15389588.2019.1591621
発　行
2019年
要　旨
Fatal brain injuries result from physiological changes in brain tissues, subsequent to primary damage caused by head impact. Although efforts have been made in past studies to estimate the probability of brain injury, none of them involved prediction of such physiological changes. The goal of this study was to evaluate the fatality prediction capability of a novel approach that predicts an increase in intracranial pressure (ICP) due to primary head injury to estimate the fatality rate using clinical data that correlate ICP with fatality rate.

Simulating cerebral edema and delayed fatality after traumatic brain injury using triphasic swelling biomechanics

著　者
AV Basilio, Peng Xu, Y Takahashi, T Yanaoka, H Sugaya, G Ateshian, B Morrison III
収　録
Traffic Inj Prev, 2019;20(8):820-825, doi: 10.1080/15389588.2019.1663347
発　行
2019年
要　旨
Contemporary finite element (FE) models, like that from the Global Human Body Models Consortium (GHBMC), have been useful for developing safety systems to reduce the severity of injuries in motor vehicle crashes (MVCs), including traumatic brain injury (TBI). However, not all injury occurs during the MVC. Cerebral edema after TBI contributes to mortality by increasing intracranial pressure (ICP) and preventing adequate cerebral blood supply. The focus of this study was to model post-traumatic cerebral edema and subsequent mortality due to increased ICP.

Computational Modeling of Bridging Vein Rupture and Acute Subdural Hematoma Growth

著　者
D Zeng, AV Basilio, T Yanaoka, LA Pichay, G Ateshian, S Maas, B Morrison III
収　録
Ann Biomed Eng, 2025 Dec;53(12):3329-3344, doi: 10.1007/s10439-025-03860-6
発　行
2025年
要　旨
Due to relative motion between the skull and brain caused by mechanical impact to the head during traumatic brain injury (TBI), bridging vein (BV) rupture can occur, resulting in the formation of acute subdural hematoma (ASDH). ASDH is associated with worse clinical outcomes and higher mortality because the resulting blood clot compresses surrounding brain tissue, exacerbating secondary injuries such as cerebral edema and ischemia. In this study, we developed a computational schema to predict BV rupture and model ASDH growth. Leveraging the deformation in the cerebrospinal fluid (CSF) layer in the Global Human Body Models Consortium (GHBMC) finite element head model to evaluate relative motion at the brain–skull interface, we introduced a novel BV rupture prediction approach based on statistical measures of the strain of these CSF elements. This approach attempts to account for the population variability in BV geometry. Validation using real-world crash accident reconstruction data demonstrated good predictive performance. Based on BV rupture predictions, we modeled ASDH growth, in which hematoma expansion was driven by the simulated patient-specific intracranial pressure (ICP) response due to primary injury and secondary injuries. Hematoma growth ceased once local hematoma cavity pressure equilibrated with ICP. Simulation results produced significant hematoma expansion with greater ICP elevation, a critical indicator for high mortality rate in the clinic. The computational schema developed in this study provides a foundation for future studies to improve the prediction of mortality rate for patients with BV rupture and ASDH after TBI, which can aid in safety system design.

Investigation on Generational Difference of Intracranial Responses Related to Traumatic Brain Injuries Using Age-Specific Human Head/Brain FE Models

著　者
T Yanaoka and Y Dokko
収　録
SAETechnical Paper 2014-01-0485, 2014, Detroit, U.S.A., https://doi.org/10.4271/2014-01-0485
発　行
2014年
要　旨
The high frequency of fatal head injuries of elderly people in traffic accidents is one of the important issues in Japan. One of the causes may be vulnerability of the aged brain. While a human head/brain FE model is a useful tool to investigate head injury mechanism, there has not been a research result using a model considering the structural and qualitative changes of the brain by aging. The objective of this study was to clarify the generational difference of intracranial responses related to traumatic brain injuries (TBI) under impact loading. In this study, the human head/brain FE models in their twenties (20s) and seventies (70s) were used. They were developed by reflecting the age-specific characteristics, such as shape/size and stiffness of brain matter and blood vessels, to the baseline model developed by Global Human Body Models Consortium (GHBMC) LLC. The generational difference of intracranial responses related to TBI, such as cumulative strain damage measure (CSDM), dilatational damage measure (DDM) and elongation of bridging vein (BV), were studied using the models. From the study of the generational difference of intracranial responses related to TBI, the following were found: 1) CSDM of 70s was 1.05 times greater than that of 20s; 2) DDM of 70s was 0.97 times smaller than that of 20s; 3) Elongation of BV of 70s was 1.04 times greater than that of 20s; and 4) Further investigation is needed, considering both the magnitude of the responses and the tolerance of the tissue when considering the injury risk.

Investigation of a Simplified Vehicle Model that Can Reproduce Car-Pedestrian Collisions

著　者
H Asanuma, Y Takahashi, M Ikeda and T Yanaoka
収　録
SAE Technical Paper 2014-01-0514, 2014, https://doi.org/10.4271/2014-01-0514.
発　行
2014年
要　旨
Japanese accident statistics show that despite the decreasing trend of the overall traffic fatalities, more than 1,000 pedestrians are still killed annually in Japan. One way to develop further understanding of real-world pedestrian accidents is to reconstruct a variety of accident scenarios dynamically using computational models. Some of the past studies done by the authors' group have used a simplified vehicle model to investigate pedestrian lower limb injuries. However, loadings to the upper body also need to be reproduced to predict damage to the full body of a pedestrian. As a step toward this goal, this study aimed to develop a simplified vehicle model capable of reproducing pedestrian full-body kinematics and pelvis and lower limb injury measures. The simplified vehicle model was comprised of four parts: windshield, hood, bumper and lower part of the bumper. Several different models were developed using different combinations of geometric and stiffness representation. A unique model called a multi-layer model developed in this study represented each of the hood and the windshield with a stack of the panel representing the entire area of these components, while applying localized stiffness characteristics and contact definition with a particular pedestrian body region that contacts with the layer represented by the stiffness characteristics. These models were made to collide with the human FE model, and pelvis and lower limb injury measures and full-body kinematics were compared with those from the simplified vehicle models. The results of the comparisons showed that the multi-layer model provided a more realistic contact interaction between the pedestrian body and the vehicle by eliminating the gap between adjacent panels due to geometric division of a large vehicle body panel.

Investigation on an Injury Criterion Related to Traumatic Brain Injury Primarily Induced by Head Rotation

著　者
T Yanaoka, Y Dokko and Y Takahashi
収　録
SAE Technical Paper 2015-01-1439, 2015, Detroit, U.S.A., https://doi.org/10.4271/2015-01-1439.
発　行
2015年
要　旨
The high frequency of fatal head injuries is one of the important issues in traffic safety, and Traumatic Brain Injuries (TBIs) without skull fracture account for approximately half of them in both occupant and pedestrian crashes. In order to evaluate vehicle safety performance for TBIs in these crashes using anthropomorphic test dummies (ATDs), a comprehensive injury criterion calculated from the rotational rigid motion of the head is required. While many studies have been conducted to investigate such an injury criterion with a focus on diffuse brain injuries in occupant crashes, there have been only a limited number of studies focusing on pedestrian impacts. The objective of this study is to develop a comprehensive injury criterion based on the rotational rigid body motion of the head suitable for both occupant and pedestrian crashes. In this study, an injury criterion that correlates with the tissue-level predictors of diffuse brain injuries in both occupant and pedestrian crashes is proposed by incorporating the change of the rotational velocity during a certain maximum time. A mid-sized male human head/brain FE model was used to investigate the correlation between injury criteria based on the rotational rigid body motion of the head and the tissue-level predictors of diffuse brain injuries such as Cumulative Strain Damage Measure (CSDM) and Maximum Principle Strain (MPS) to compare the applicability of the proposed criterion to that of the currently proposed injury criteria.

A Parametric Study of Age-Related Factors Affecting Intracranial Responses under Impact Loading Using a Human Head/Brain FE Model

著　者
T Yanaoka and Y Dokko
収　録
Proceedings of IRCOBI Conference, 2013, Gothenburg, Sweden, IRC-13-50
発　行
2013年
要　旨
The high frequency of fatal head injuries in elderly people in traffic accidents is one of the important issues in Japan. One of the causes may be vulnerability of the aged brain. While a human head/brain FE model is a useful tool to investigate head injury mechanisms, there has not been such a model considering the structural and qualitative changes of the brain caused by aging. The objective of this study was to clarify the influence of intracranial changes on intracranial responses relating to brain injuries, which could be the basic knowledge to develop a head/brain model capable of representing injury mechanisms of the aged brain. The influence of eight factors representing structural and material features on intracranial response was parametrically studied using a human head/brain FE model. Furthermore, influence of the impact direction was studied swapping the axis in the model along which the acceleration pulses were applied. The following results were found: 1) PAC (Pia-Arachnoid Complex) layer volume and stiffness of bridging vein (BV) had a strong influence on elongation of BV, 2) stiffness of the brain strongly influenced dilatational damage measure (DDM) and 3) stiffness of the brain and PAC layer volume had a strong influence on cumulative strain damage measure (CSDM).

Investigation of Fatality Probability Function Associated with Injury Severity and Age

著　者
T Yanaoka, A Akiyama and Y Takahashi
収　録
Proceedings of IRCOBI Conference, 2014, Berlin, Germany, IRC-14-11
発　行
2014年
要　旨
The goal of this study is to develop a fatality probability function associated with injury severity and age, which could provide a useful method to estimate the fatality rate accurately. Seven types of logistic regression models were taken into consideration. The results of the estimations from the 7 logistic regression models were compared to select the best fit regression model by using the data from the United States (US) accident statistics National Automotive Sampling System Crashworthiness Data System (NASS - CDS) in year 2001. In addition, the constant coefficients of the model best fit to the year 2001 data were replaced by regression functions as a function of year to develop a model incorporating the effect of the year change. The following results were found: (1) the best fit regression model was a function of maximum Abbreviated Injury Scale (AIS) of each body region and age; (2) the accuracy of the regression model was improved by applying regression functions of the coefficients as a function of the year; and ) the regression functions of the coefficients show that the fatality rate decreases with each progressing year.

Development of a Full-Body Human FE Model for Pedestrian Crash Reconstructions

著　者
Y Takahashi, H Asanuma, T Yanaoka
収　録
Proceedings of IRCOBI Conference, 2015, Lyon, France, IRC-15-63
発　行
2015年
要　旨
The goal of this study is to develop a full‐body human Finite Element (FE) model with the enhanced biofidelity and the numerical robustness necessary for use in dynamic car–pedestrian accident reconstructions in various impact scenarios. An FE model for the pelvis and lower limbs in a standing position developed in the authors past study was combined with FE models for bones and ligaments in the upper body taken from an occupant model. The biofidelity of the combined model was further enhanced and validated against experiments. Each body region of the full‐body model was validated in multiple loading conditions, including neck bending, thoracic impact, isolated pelvis impact, thigh and leg bending, knee bending, knee ligament tension, and ankle joint rotation. The full‐body model was subjected to lateral and frontal impacts at 70 km/h against a simplified car model representing a stiff front‐end structure, showing that the model is robust enough to simulate high speed impacts in different pedestrian orientations.

MRI based head surface mesh of young and old people for finite element analysis

著　者
K Sato, B Thyreau, T Yanaoka, R Kawashima, et al
収　録
The 19th Annual Meeting of the Organization for Human Brain Mapping, 2013.
発　行
2013年
要　旨
東北大の加齢医学研究所で所有している脳画像データベースを元に、成人(20代)、高齢者(70代)の平均脳形状を作成し、その特徴を比較したものです。この論文を参照として、頭部モデルの脳形状を成人と高齢者それぞれに変更して衝撃入力に対する脳内応答の変化を見たのが、その後に出ている以下の論文となります。
「柳岡 寿幸, 独古 泰裕, "年代別人体頭部有限要素モデルを用いた 加齢による脳内応答の変化に関する研究", 自動車技術会論文集, 2014, 45巻, 6号, p. 1111-1116」「T Yanaoka and Y Dokko, "Investigation on Generational Difference of Intracranial Responses Related to Traumatic Brain Injuries Using Age-Specific Human Head/Brain FE Models," SAE Technical Paper 2014-01-0485, 2014, Detroit, U.S.A.」

Estimation of the Effect of Autonomous Emergency Braking Systems for Pedestrians on Reduction in the Number of Pedestrian Victims

著　者
T Yanaoka and Y Takahashi
収　録
Proceeding of 25th ESV Conference, 2017, Detroit, United States of America, Paper Number 17-0017
発　行
2017年
要　旨
Considering the significant sensitivity of impact velocity to pedestrian casualty rate, it is important to accurately estimate the effect of autonomous emergency braking systems for pedestrians (AEBP) on the casualty rate to further reduce pedestrian victims. This study developed a methodology to estimate the reduction of pedestrian casualties resulting from AEBP activation by applying the exact logic of a particular AEBP system to Japanese accident statistics. Focus was given to the sensitivity of applying the exact logic of a particular AEBP system and the parameters considered in the fatality/serious injury rate prediction to the estimated effect of the AEBP system. Due to the difference in accident parameters relevant to the function of the AEBP system and the impact configurations and outcomes, two sets of accident data, which include different accident parameters with some overlap, were used to estimate the distribution of impact speed and the reduction in the fatality/serious injury rates. One dataset was used to estimate the impact speed distribution by applying the exact logic of a particular AEBP system, and the other dataset was used to determine the fatality/serious injury rates. The reduction of the number of victims was estimated by lumping the estimated impact speed distribution and the estimated fatality/serious injury rates into the accident scenarios defined by the common parameters. The sensitivity to the reduction in the number of victims was investigated for the application of the exact logic, and the parameters considered in the estimation of the fatality/serious injury functions. The estimated reduction in the number of victims was 20% for the AEBP system investigated in this study. Relative to the use of a simple logic of the system, the application of the exact logic of the system resulted in the difference in the estimated reduction of fatalities and serious injuries by 5% and 12%, respectively. The most severely injured body region, the pedestrian age, and the vehicle category are the most sensitive to the estimated effect among the accident parameters used in the dataset relevant to impact configurations and outcomes except for the vehicle travel speed.

A study of injury criteria for brain injuries in traffic accidents

著　者
Y Takahashi and T Yanaoka
収　録
25th ESV conference, 2017, Detroit, United States of America, Paper Number 17-0040
発　行
2017年
要　旨
The goal of this study was to develop a motion-based injury criterion for brain injuries derived from the material response of the brain tissue, under the assumption that impact response of the brain tissue can be characterized by a standard linear solid. Focus was given to brain injuries that are deemed to correlate with the strain of the brain tissue, including subarachnoid hemorrhage, intracerebral hemorrhage and diffuse axonal injury. The criterion is based on rotational motion of the head because of incompressibility of the brain tissue that allows large strain primarily in rotation. The stiffness and damping parameters of a one-dimensional Kelvin model were determined for each axis of rotation of the head in such a way that scaled displacement time history matches strain time history of the brain tissue predicted by the Global Human Body Models Consortium (GHBMC) head-brain model. The convolution integral of the impulse response of the model was used to predict strain time history of the brain when an arbitrary rotational acceleration time history is applied to the head. The maximum value of the predicted strain was defined as a new brain injury criterion (Convolution of Impulse response for Brain Injury Criterion; CIBIC). Head rotational acceleration data were taken from a number of crash test data representing full frontal, oblique frontal and side impacts along with pedestrian impact simulation results to investigate correlation between the values of various brain injury criteria, including CIBIC, and the maximum principal strain from the head-brain model. The injury criterion proposed by this study, CIBIC, resulted in a better correlation with the predicted maximum principal strain of the brain relative to those proposed by past studies in all of the four crash configurations (R2 ranging from 0.624 to 0.864). It was also found that the coefficient of determination was smaller for the impact conditions resulting in multiple or long-duration loading than other impact configurations representing single short-duration loading.

Investigation of Strain-Induced Brain Injury Mechanism in Simulated Car Accidents

著　者
T Yanaoka, Y Takahashi, Sugaya H, Kawabuchi T
収　録
Proceeding of 26th ESV Conference, 2019, Eindhoven, Netherlands, Paper Number 19-0070
発　行
2019年
要　旨
Further reduction of brain injuries is crucial to diminish traffic fatalities. Past studies suggest that strain of incompressible brain tissue is generated mainly due to head rotation. Accident statistics show a higher rate of pedestrian fatalities resulting from strain-induced brain injuries in accidents with AIS 2+ brain injuries than that of car occupants. One factor for this difference would be larger translation and rotation of an unrestrained pedestrian body than those of a restrained car occupant. This study aimed to clarify the influence of whole body kinematics on the brain strain in pedestrians and occupants. Time histories of the head translational and rotational accelerations were taken from the NHTSA crash test database for full frontal and MDB side impacts. Pedestrian crash simulations were conducted for frontal and side impacts using a human, small-sedan and SUV FE models to obtain head acceleration time histories. These time histories were applied to the skull of the GHBMC head/brain model. The time histories of the maximum principal strain from the GHBMC model were compared between occupants and pedestrians in the same impact direction. The body kinematics and the rotational velocity of the head were also compared to identify factors for the difference in the time history patterns of the maximum principal strain. In addition, these time histories were compared to that of the CIBIC (Convolution of Impulse response for Brain Injury Criterion) criterion developed in a previous study under each of the four conditions. Peaks of brain strain were identified in both head pre-impact and impact phase for pedestrian while that was identified only in head impact phase for occupant, regardless of the impact direction. The flip of the rotational direction of the head in the head pre-impact phase was found only in pedestrian, likely resulting in the peak of brain strain prior to the head impact. This trend applied regardless of the direction of impact. The time history of the CIBIC criterion provided waveform patterns similar to the maximum principal strain time history in all impact conditions. Peaks of brain strain in both head pre-impact and impact phase in pedestrian identified in this study would require reduction of peaks in both phases. A criterion predicting time history of brain strain, such as CIBIC, was found to be an effective tool to address reduction of peaks in multiple phases seen in pedestrian. These findings would lead to novel pedestrian safety technologies that control pedestrian kinematics to reduce the primary peak.

Influence of Time Constants and Directional Interaction of a Kinematics-based Brain Injury Metric on Its Predictive Capability of Brain Strain Response in Car Crashes

著　者
T Yanaoka
収　録
Proceeding of 27th ESV Conference, 2023, Yokohama, Japan, Paper Number 23-0183
発　行
2023年
要　旨
Among the studies focusing on criteria for brain injuries induced by the rotational motion of the head, one of the recent studies has compared the predictive capability of various injury criteria proposed by different studies, with the results showing that the best predictor depends upon specific impact configurations. This suggests the need for a more robust injury criterion across a variety of impact configurations with different duration of an impact event. The aim of this study is to investigate the effect of incorporating additional time constants and modifying directional interactions on the predicting accuracy of the physical model-based criterion called CIBIC (Convolution of Impulse Response for Brain Injury Criterion) proposed by the author’s group. A Maxwell model was parallelly added to the simplified physical model (standard linear solid) of the CIBIC criterion to improve the time-dependent responses. One simplest candidate formulation of the cross-terms was tried to replace the originally used root sum square to combine the three components of the strain. The Global Human Body Models Consortium (GHBMC) head/brain model was used to obtain the target response of the maximum principal strain (MPS). A step function with the magnitude of 10,000 rad/s2 was used to optimize the spring and damping coefficients. The spring and damping coefficients were optimized by maximizing the CORA (CORrelation and Analysis) score. The modified CIBIC was further validated against the GHBMC model using a total of 256 time histories of the head rotational acceleration representing those of the four groups of load cases (occupants in fullfrontal, oblique-frontal and side impacts as well as pedestrian impacts). The coefficient of determination calculated from the correlation of peak MPS and the average value of the CORA score were compared between the original and the modified CIBIC. The modified CIBIC with the modified time constants was found to improve both assessment metrics for all of the four groups of the load cases, while both assessment metrics predicted by the modified CIBIC with the directional interaction was not improved. The effect of the modifications shown by the modified CIBIC suggest that further consideration of the directional interaction is needed to develop a robust criterion, requiring thorough investigations on the method to combine the responses of the three axes.

METHODOLOGY TO PREDICT STRAIN OF BRIDGING VEIN DUE TO ROTATION OF HEAD

著　者
Y Takahashi and T Yanaoka
収　録
27th ESV Conference, 2023, Yokohama, Japan, Paper Number 23-0261
発　行
2023年
要　旨
The brain stem can be damaged by the herniation of the brain tissue, potentially leading to fatality. Mass lesion could lead to fatality due to brain stem herniation, necessitating the prediction of the strain of the bridging veins (BVs). A number of trabecula forming a web-like structure of the sub-arachnoid space (SAS) may allow the assumption that the strain of the BVs correlates with that of the SAS. The objective of this study is to investigate the predictive capability of the strain in both the brain parenchyma (BP) and the SAS using a simplified physical model based on the CIBIC (Convolution of Impulse Response for Brain Injury Criterion) criterion proposed by the authors. A viscoelastic model consisting of a series of two sets of standard linear solids (SLSs) used in the CIBIC criterion (extended version of CIBIC; e:CIBIC) was developed to represent both the BP and the SAS. The Global Human Body Models Consortium (GHBMC) head/brain model was used to obtain the target response of the maximum principal strain (MPS) in the BP and the SAS. Three angular acceleration time histories to be used to optimize model parameters were determined by combining twenty sine waves with the frequency ranging 10-200 Hz. The optimization of the spring and damping coefficients was performed by maximizing the CORA (CORrelation and Analysis) score for the time histories of the MPS in the BP and the SAS obtained from the GHBMC model. The optimized e:CIBIC was further assessed against a total of 256 sets of head rotational acceleration time histories obtained from frontal and side impacts and pedestrian impacts. The assessment was performed for the coefficient of determination of the correlation of the peak MPS with the GHBMC model along with the average value of the CORA score with the strain in both the BP and the SAS. The two assessment metrics were also compared against the original CIBIC criterion for the brain strain to clarify improved prediction. The results of the performance assessment using the two metrics showed that e:CIBIC is capable of simulating the MPS in the BP with an accuracy similar to the original CIBIC. It was also found that the predictive capability of e:CIBIC for the MPS in the SAS is higher than that of the original CIBIC for the MPS in the BP. This study revealed that e:CIBIC with the two sets of the SLS in series is capable of predicting the strain in both the SAS and the BP simultaneously. The results obtained in this study is dependent upon the validity of the head/brain FE model used. The relationship between the strain of the SAS and the probability of BV failure needs to be further investigated.