Three Years Old Child Neck Finite Element Modelisation

Abstract

Despite of recent progresses in occupant safety, the protection of children is still not optimal. To offer a better comprehension of child injury mechanisms, we developed a human-like finite element of a three years old child's neck. The subject was scanned with a medical scanner. The images were first semiautomatically segmented in order to extract the soft tissues and the bones. In the second step, we separate the different bones slice by slice on the geometry previously reconstructed. The anatomic structures are identified and each vertebra is reconstructed independently with special attention for the articular process. In a second step, we have generated an original meshing on the previous geometry to obtain a finite element model of the child's neck. The anatomical structures incorporated are the head, the seven cervical vertebrae (C1–C7), the first thoracic vertebra (T1), the intervertebral discs and the principle ligaments which are modelled using non-linear shock-absorbing spring elements. The stiffness values used are taken from literature, and scaled down using scale factors from Irwin (1997). This model incorporates 7340 shell elements to model the eight vertebrae, the head and 1068 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 were not available, we realized some Q3 dummy component sled tests. The accelerometric responses of the head model were similar to those recorded experimentally with a Q3 dummy neck in frontal impact direction.