This study proposes a theoretical modal analysis of a finite element model of the human head in its sagittal plane. The study presents the result applications to the crash biomechanics field. This approach allowed the determination of the mechanical properties of the material used to model the subarachnoid space. The aim is to obtain the first natural frequency and the mode shape in accordance with the mechanical impedance recorded on the human head in vivo. The main result of the analysis is reached at the mode shape level, in particular with respect to its quasi insensitivity to mechanical properties of the materials involved. The first mode shape reveals a rotation of the brain mass around a point located at the center of a circle. This motion causes significant brain stresses at the frontal lobes level, mainly at their interface with the orbital floor. The study shows how occipital impacts cause frontal injuries. This result is illustrated in the temporal field by calculating both the brain motions and intracerebral stresses under impact conditions.
Abstract