Brain kinematics in physical model tests with translational and rotational acceleration

Abstract

Abstract Brain responses in closed-head impact were simulated in a physical model of the parasagittal section. During head impact, high-speed movies filmed motion of grid-points in the transparent silicone brain gel that is separated from the skull by a thin liquid layer representing the CSF. Gel displacement and Green-Lagrange strain were calculated from digitised films. For 10,200 r/s2 angular acceleration, gel displacement and slip along the skull boundary were +/-15 mm near the perimeter. Tensile strain reached 40-70% near the base of the skull, and shear strain was 40-50% in the frontal and occipital regions. For 200 g linear acceleration, there was >20 mm brain displacement as the skull compressed the frontal region, and gel separated from the occiput. Tensile strain was 15-25% in the frontal, central and occipital regions, and shear strain was <15%. Brain injury mechanisms are discussed. The physical model tests are well-documented, and may help refine finite element models of brain displacement and deformation during closed-head head impact.