Remy Willinger a Professor at University of Strasbourg has activity ranges from biological tissues identification and modelling to human body characterization followed by lumped and distributed modelling. Physical modelling i.e. dummy development. Once validated the numerical and physical models are used for theoretical and experimental accident reconstruction in order to derive tolerance limits relative to specific injury mechanisms. Human models are also coupled to protective systems in order to optimise them in respect to biomechanical criteria. Most of his work addressed the skull-CSF-brain complex, cervical column injury investigatio, neck characterisation and modelling effort. 

Traumatic brain injury is the leading cause of death and permanent impairment over the last decades. In both the severe and mild TBI, diffuse axonal injury (DAI) is the most common pathology. Computation of axon elongation by using finite element head model in numerical simulation can enlighten the DAI mechanism and help to establish advanced tissue level head injury criteria. The main objective of this research is to propose a brain injury criterion based on multiscale computation of axonal elongation under real world head trauma.

In a very first step a literature review of head trauma biomechains is presented to introduce existing and recently proposed head injury criteria based on global head kinematics parameters, in terms of transmational motion, rotational motion and combined kinematics. The state of the art in the domaine of head FE modeling is also shown as well as the model validation aspects. Finally focus is on the development of Strasbourg University FE head model (SUFEHM).

For this model the modelling technic of the three layered skull and the establishement of a skull fracture criteria based on real world skull fracture data will be shown. Comming to the modelling of the brain, a new generation of models will be introduced. The implementation of new medical imaging data such as, fractional anisotropy and axonal fiber orientation from DTI into the FE brain model was performed to improve the brain constitutive material law with more efficient heterogeneous anisotropic visco-hyper-elastic material law and enables it to compute axon elongation at the time of impact.

An extensive well documented real-world head trauma simulation exercise was performed with this  advanced head FE model including the computation of axonal elongation. Based on the statistical analysis, axonal strain was shown to be  the most relevant metric to predict moderate DAI. It was showed that the threshold value in terms of axonal strain for a 50% risk of moderate DAI(AIS2+) is 15% of axon strain.

The transfer of this novel head injury preduction tool towards industry and standard organisation will be adresses including virtual testing in the automotive environment and new experimental versus numerical helmet test methods.