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Importance of neck muscle tonus in head kinematics during pedestrian accidents
KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.ORCID iD: 0000-0001-7908-6270
KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.ORCID iD: 0000-0002-0980-4051
KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.ORCID iD: 0000-0003-0125-0784
2013 (English)In: 2013 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury, 2013, 747-761 p.Conference paper, Published paper (Refereed)
Abstract [en]

Unprotected pedestrians are an exposed group in the rural traffic and the most vulnerable human body region is the head which is the source of many fatal injuries. This study was performed to gain a better understanding of the influence that the neck muscle tonus has on head kinematics during pedestrian accidents. This was done using a detailed whole body FE model and a detailed FE vehicle model. To determine the influence of the muscle tonus a series of simulations were performed where the vehicle speed, pedestrian posture and muscle tonus were varied. Since the human reaction time for muscle activation is in the order of the collision time, the pedestrian was assumed to be prepared for the oncoming vehicle in order to augment the possible influence of muscle tonus. From the simulations performed, kinematic data such as head rotations, trajectory and velocities were extracted for the whole collision event, as well as velocity and accelerations at head impact. These results show that muscle tonus can influence the head rotation during a vehicle collision and therefore alter the head impact orientation. The level of influence on head rotation was in general lower than when altering the struck leg forward and backward, but in the same order of magnitude for some cases. The influence on head accelerations was higher due to muscle tonus than posture in all cases.

Place, publisher, year, edition, pages
2013. 747-761 p.
Keyword [en]
Finite element method, Head kinematics, Muscle tonus, Pedestrian accident
National Category
Other Medical Sciences not elsewhere specified
Identifiers
URN: urn:nbn:se:kth:diva-133441Scopus ID: 2-s2.0-84896633346OAI: oai:DiVA.org:kth-133441DiVA: diva2:661270
Conference
International Research Council on the Biomechanics of Injury Conference, IRCOBI 2013; Gothenburg; Sweden; 11 September 2013 through 13 September 2013
Note

QC 20140609

Available from: 2013-11-01 Created: 2013-11-01 Last updated: 2017-10-12Bibliographically approved
In thesis
1. Understanding Boundary Conditions for Brain Injury Prediction: Finite Element Analysis of Vulnerable Road Users
Open this publication in new window or tab >>Understanding Boundary Conditions for Brain Injury Prediction: Finite Element Analysis of Vulnerable Road Users
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Vulnerable road users (VRUs) are overrepresented in the statistics on severe and deadly injuries in traffic accidents, most commonly involving the head. The finite element (FE) method presents the possibility to model complex interactions between the human body and vehicles in order to better understand the injury mechanisms. While the rapid development of computer capacity has allowed for increasingly detailed FE-models, there is always a benefit of reducing the studied problem. Due to its material properties, the brain is more sensitive to rotational motion than to purely linear, resulting in complex injury causation. When studying brain injuries caused by a direct impact to the head, simulations using an isolated head model significantly increases efficiency compared to using a complete human body model. Also evaluation of head protective systems uses isolated mechanical head representations. It is not, however, established the extent to which the boundary conditions of the head determine the outcome of brain injuries.

FE models of both the entire human body and the isolated head were used in this thesis to study the effect of the body, as well as active neck muscle tension, on brain injury outcome in VRU accidents. A pediatric neck model was also developed to enable the study of age-specific effects. A vehicle windscreen model was developed to evaluate the necessity of capturing the failure deformation during pedestrian head impacts.

It was shown that the influence of the neck and body on brain injury prediction is greater in longer duration impacts, such as pedestrian head-to-windscreen impacts with an average difference of 21%. In accidents with shorter duration impacts, such as head-to-ground bicycle accidents, the average influence was between 3-12%. The influence did not consistently increase or limit the severity, and was dependent on the degree of rotation induced by the impact, as well as the mode of deformation induced in the neck. It was also shown that the predicted brain injury severity is dependent on capturing the large deformations of fractured windscreen, with the greatest effect near the windscreen frame. The pediatric neck model showed a large effect of age-dependent anatomical changes on inertial head loading, making it a promising tool to study the age-dependent effects in VRU accidents.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. 83 p.
Series
TRITA-STH : report, ISSN 1653-3836 ; 2017:11
Keyword
Brain injuries; Vulnerable Road Users; windscreen impacts; Finite Element Analysis; pedestrian accidents; cycling accidents; pediatric neck
National Category
Other Medical Engineering
Research subject
Applied Medical Technology
Identifiers
urn:nbn:se:kth:diva-215643 (URN)978-91-7729-568-6 (ISBN)
Public defence
2017-11-06, T2, Hälsovägen 11C, Huddinge, 10:00 (English)
Opponent
Supervisors
Note

QC 20171013

Available from: 2017-10-13 Created: 2017-10-12 Last updated: 2017-10-16Bibliographically approved

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Alvarez, VictorFahlstedt, MadelenKleiven, Svein

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