Investigation of Loss of Consciousness Induced by Gravity Acceleration on the Human Brain

Abstract

Traumatic Brain Injuries (TBI’s) are any disorder in a brain’s functionality that can be caused by numerous reasons, including motor-vehicle crashes, falls, and assaults. Impractical in-vivo head injury experiments compel bio- engineers to develop a robust, accurate, and efficient computer model. In this study, bovine brain samples were tested under a confined compression testing machine. Consequently, the result from unconfined compression tests, at quasi-static strain rates of e=0.0004 s-1, e=0.008 s-1, and e=0.4 s-1, and a stress relaxation test under unconfined uniaxial compression with a e=0.67 s-1 ramp rate were utilized for fitting brain tissue model. The tissue model employs Drucker stability criteria and conventional hyperelastic models. A finite element model was also developed and validated by experimental data to examine the experiments’ friction effect. Furthermore, the extracted brain tissue model was employed in a 3D head injury model. The 3D model was employed to examine the effect of +Gz acceleration on the human brain and present damage threshold based on loss of consciousness in HIC and Maximum Brain Pressure criteria. It is shown that the relative difference between simulation results at friction coefficient of μ=0.5 and μ=0.0 are less than 20%, and the ramp rate variation has a slight effect on normalized shear modulus. Moreover, Head modeling results revealed that the Maximum Brain Pressure ≥ 3.1 KPa and HIC ≥ 30 are a representation of loss of consciousness.