Traumatic brain injury (TBI) occurs as result of a sudden trauma to the brain due to impacts or the rapid movement of the head caused by falls, accidents, sports contacts, and physical assaults. TBI can lead to long-term cognitive, physical, and neurological impairments and hence should be prevented. While head kinematics can be experimentally estimated - to a good extent - using dummy heads, assessment of tissue responses of the brain in terms of the intracranial pressure, shear stresses, and strains is technically and morally challenging. Accordingly, due to complications of experimental tests, computational methods such as finite element analysis (FEA) have extensively been used in the last decade to study the injury mechanisms associated with TBI. However, the fidelity of these models is still a concern when conclusions are to be drawn based on numerical results. One major aspect of each computational work is the implementation of accurate material models which can mimic the real behavior of biological tissues. Skull protects the brain against injury by attenuating the transferred load to the intracranial space upon an impact to the head. Several material properties have been used for skull in the literature in the context of impact induced TBI. These studies have used a wide range of densities and Young’s moduli for the skull; however, they have used different head models and loading conditions. Our study aims to investigate the sensitivity of a FE head model to skull material properties. To this end, North Dakota State University Finite Element Head Model (NDSUFEHM) was exposed to an identical impact using three different sets of material properties in terms of density and Young’s modulus
taken from the well-substantiated impact TBI studies. A frontal impact scenario was developed by impacting the head moving at 2.5 m/s against a rigid wall 45 degrees about its horizontal plane. Time histories of ICP and shear stress at the location of maximum value were recorded and compared for all three material properties sets. Our primary results predicted noticeable differences among pressure and shear responses both in terms of the peak values and their pattern. Our results suggested the need for a unique set of skull properties in order to improve the biofidelity of FE models.

Sensitivity Analysis of a Finite Element Head Model to Skull Material Properties in the Study of Traumatic Brain Injury