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Three-year-old child neck finite element modelization

  • Raphaël DupuisEmail author
  • Frank Meyer
  • Caroline Deck
  • Rémy Willinger
Original Article

Abstract

Despite the recent progresses in occupant safety, protection of children is not still optimal. To offer a better understanding of child injury mechanisms, the present study proposes a human-like finite element model of a 3-year-old child neck. The subject underwent scanning. The images were first segmented semi-automatically in order to extract the soft tissues and the bones. In the second step, we separated the different bones slice by slice on the geometry previously reconstructed. The anatomic structures were identified and each vertebra was reconstructed independently with special attention to the articular process. In the third step, we generated an original meshing on the previous geometry to obtain a finite element model of the child’s neck. The modelled anatomical structures are the head, the seven cervical vertebrae (C1–C7), the first thoracic vertebra (T1), the intervertebral discs and the principal ligaments which were modelled using non-linear shock-absorbing spring elements. The stiffness values used were taken from the literature, and scaled down using scale factors from Irwin. This model incorporates 7,340 shell elements to model the 8 vertebrae, the head and 1,068 solid 8-node elements to model the intervertebral discs. Contact between the articular surfaces is represented by interfaces permitting frictionless movement. Since this study does not aim to reproduce bone fractures, we have modelled the cervical vertebrae as rigid bodies. Given that validation data was not available, the model validation was conduced against crash test dummy component sled tests. The accelerometric responses of the head model were similar with those recorded experimentally with a Q3 dummy neck in backward, frontal and lateral impact direction.

Keywords

Children Finite element model Neck Crash Validation 

Modélisation par éléments finis d’un rachis cervical d’enfant

Résumé

Malgré l’évolution récente des systèmes de protection dans les automobiles, les traumatismes du rachis cervical de l’enfant restent encore un problème d’actualité. Le sujet de cette étude est donc la création et la validation d’un modèle éléments finis tridimensionnel détaillé du rachis cervical d’un enfant de trois ans, destiné à améliorer la compréhension des mécanismes lésionnels en situation de choc. Pour ce faire, nous sommes partis de coupes scanographiques; les images ont d’abord été seuillées de manière semi-automatique pour extraire les parties osseuses. Les vertèbres ont été identifiées coupes par coupes sur la base de la géométrie ainsi reconstruite. Dans un second temps, à partir de la géométrie obtenue, nous avons généré un maillage original comprenant le crâne, les sept vertèbres cervicales, la première vertèbre thoracique, les disques intervertébraux et les principaux ligaments. Les huit vertèbres ainsi que le crâne ont été modélisés par des éléments coques, les disques intervertébraux par des éléments volumiques et les ligaments par des éléments ressorts. Les éléments osseux se sont vus déclarés en tant que corps rigides puisque l’étude ne prend pas en compte la rupture osseuse. Les ligaments ont été modélisés par des ressorts viscoélastiques non-linéaires dont les valeurs de raideur sont issues de la littérature et ont été ajustés selon les coefficients d’échelle de Irwin. Le contact entre les surfaces articulaires est géré par des interfaces sans frottement. Du fait de l’absence de données expérimentales sur le comportement de l’enfant en situation d’impact, nous avons mené des essais chariots sur le cou d’un mannequin de crash Q3. Les réponses numériques de la tête en terme d’accélération étaient similaires à celles mesurées expérimentalement en choc avant, arrière et latéral.

Mots clés

Enfant Modèle éléments finis Cou Crash Validation 

Notes

Acknowledgements

The authors would like to acknowledge the efforts of INRETS for their contribution in the validation of the 3-year-old child neck finite element model. The development and the validation of the model were funded by the European Community under the G3RD-CT-2002-00791 CHILD project.

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Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • Raphaël Dupuis
    • 1
    Email author
  • Frank Meyer
    • 1
  • Caroline Deck
    • 1
  • Rémy Willinger
    • 1
  1. 1.Institut de Mécanique des Fluides et des SolidesUniversité Louis PasteurStrasbourgFrance

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