Parametric study of effects of brain-skull boundary conditions and brain material properties on responses of simplified finite element brain model under angular acceleration impulse in sagittal plane

In the present study, the effects of brain-skull boundary conditions on the responses of a simplified three-dimensional finite element model of a thin sagittal slice of the human head were investigated. The model was excited using a time-dependent angular velocity with a maximum of 16 rad/s (maximum angular acceleration, around 5000 rad/s2). The present study was conducted using the non-linear explicit finite element code LS-DYNA. Three methods for simulation of the brain-skull boundary conditions were investigated: 1) with brain rigidly attached to the skull; 2) using frictionless sliding contact allowing no separation between the brain and skull; and 3) direct simulation of cerebrospinal fluid CSF using a layer of eight-noded solid elements with fluid-like properties. Varying the method for simulation of the brain-skull boundary conditions appreciably affected the brain responses. However, varying parameters of a given method, such as viscosity of cerebrospinal fluid CSF and CSF-skull friction coefficient, exerted only minor effects on these responses. The present results suggest that accurate simulation of brain-skull boundary conditions requires direct representation of the subarachnoidal space/CSF as a fluid-like medium.