Thèse : Brain Injury Criteria Based on Computation of Axonal Elongation

Soutenance de thèse de doctorat : Debasis SAHOO

Équipe : MMB

Title: Brain Injury Criteria Based on Computation of Axonal Elongation

Abstract: The principal objective of this study is to enhance the existing finite element head model (FEHM). A composite material model for skull, taking into account damage is implemented in the Strasbourg University Finite Element Head Model (SUFEHM) in order to enhance the existing skull mechanical constitutive law. The skull behavior is validated in terms of fracture patterns and contact forces by reconstructing 15 experimental cases in collaboration with Medical College of Wisconsin. The new skull model is capable of reproducing skull fracture precisely. The composite skull model is validated not only for maximum forces, but also for lateral impact against actual force time curves from PMHS for the first time. The influence of mass and orientation of head during lateral impacts to the head are investigated in this study. Mass of the head has a greater influence to impact force, than angle of impact. However, both mass and orientation have significant influence on skull strain energy. The effect of rotation along vertical plane has greater influence on skull strain energy than rotation along horizontal plane. This study also proposes the implementation of fractional anisotropy and axonal fiber orientation from Diffusion Tensor Imaging (DTI) of 12 healthy patients into an existing human FE head model to develop a more realistic brain model with advanced constitutive laws. Further, the brain behavior was validated in terms of brain strain against experimental data published by Hardy et al., (2001) and (2007) and for brain pressure against Nahum et al., (1977) and Trossellie et al., (1992) experimental impacts. A reasonable agreement was observed between the simulation and experimental data. Results showed the feasibility of integrating axonal direction information into FE analysis and established the context of computation of axonal elongation in case of head trauma. A total 125 reconstructions were done by using the new advanced FEHM. Different potential parameters to predict skull fracture, concussion and D!AI were selected and their values were extracted from the simulations. The statistical analysis for advanced FEHM showed that to predict skull fracture, skull internal energy and to predict DAI, axonal strain is the best suitable parameters. The reconstructions are also conducted with the existing head model for comparison and to demonstrate the benefits of new model.

La présentation aura lieu le jeudi 19 décembre 2013 à 14h00 dans la salle des séminaires, située au sein du département de Mécanique d’ICube (4 rue Boussingault - 67000 Strasbourg).