Abstract
Research and /or Engineering Questions/Objective:
Child head injury mechanisms in vehicular impact loading conditions are not as well understood by scientists as compared to those of adult head injuries. There are major differences in biological tissue properties, growing anatomical and physiological features, and mass distribution between child and adult heads. Head injury mechanisms associated with adults may not be completely transferable to children. Investigations of child head injury mechanisms experimentally are difficult. An alternative approach is through modeling by developing a fully detailed finite element (FE) child human head model.
Methodology:
A six-year old human child head finite element model was developed and used to simulate head-to-vehicle bonnet impact condition that can occur in vehicle-pedestrian impact. The child head model was created based on CT (Computerized Tomography) scan images from a living six-year old child*. Model geometry was extracted from the CT scans through image analysis. Finite element meshes were then generated from the geometric data obtained in the CT scan image analysis process. The human child head model included full detailed anatomical features of soft tissues such as the scalp, falx, dura, pia, ventricles, corpus callosum, cerebral-spinal fluid, brain white and grey matters, and brain stem; and hard tissues such as outer and inner tables, diploe, and facial bones. Material properties of the soft and hard tissues were obtained from existing biomechanical literature. Model validation was performed by comparing predicted model responses with theoretical analysis results found in the literature. Injury responses of the child head model were predicted using LS-DYNA FE analysis code.
Results:
Child head impact responses obtained from the computational analysis such as intracranial pressure, principal strain and maximum shear strain in the brain were examined. The Head Injury Criterion (HIC), which is widely used by automotive safety and biomechanics researchers, was calculated and compared to brain tissue level injury related parameters obtained from the FE model. HIC calculated from a six-year old child Headform Impactor simulation was also compared with that of the child FE head model.
Limitations:
An important limitation of the current study is the unavailability of biological material properties for the child head tissues. Furthermore, the lack of adequate material constitutive models in the FEA code to capture a more realistic biological human head impact response poses some challenges in modeling. A more vigorous model validation will depend on the availability of cadaveric data.
What does the paper offer that is new in the field in comparison to other works of the author:
The development of the detailed six-year old human head FE model and the modeling injury response data comparisons between the human and headform presented in this paper are new.
Conclusion:
A new six-year old detailed finite element human head model has been developed and preliminary validation of the model has been done theoretically. Injury responses obtained from the child head model were compared to those of headform. The study results can potentially help vehicle safety and biomechanics researchers better understand child head injury mechanisms.
KEYWORDS – Head injury; Pedestrian impact; Six-year old; Finite element