Biofidelic finite element modelling of brain trauma: Importance of the scalp in simulating head impact

Finite element head models represent a valuable tool to investigate brain injury due to head impacts. A biofidelic model is, therefore, necessary to obtain accurate and realistic results. Recent work has highlighted the importance of the scalp in head impact kinematics, particularly for oblique head impacts, where high rotational accelerations are experienced. The present work reports the development of a biofidelic finite element head model which, among other refinements, accurately reflects the mechanical and sliding properties of the scalp. The original University College Dublin Brain Trauma Model (UCDBTM), first published in 2003, has been refined and improved in several ways: (i) the mechanical properties of several components of the head were updated based on recent experimental studies, (ii) a low coefficient of friction (0.06) was introduced between the scalp and skull to better reflect anatomical sliding conditions. Additionally, the scalp-helmet coefficient of friction was set to 0.3, (iii) the mesh of the entire model was refined, increasing the number of elements by an order of magnitude from 28,286 to 184,261, and (iv) accelerometer elements were included at the centre of gravity of the head model. This enables a direct comparison between experimental measurements of linear and rotational accelerations made using instrumented headforms and the present finite element head model. The model was validated using published experimental data and subsequently used to simulate three well-documented real-world concussive head injury accidents. Results showed that the brain stresses and strains predicted using the current version (V2.0) of the UCDBTM correspond well with values for concussion reported in literature.