Fluid–Structure Interaction Analysis of Brain Tissue During Head Impacts Using Newtonian and Non-Newtonian Cerebrospinal Fluid Models

Abstract

Traumatic brain injury (TBI) caused mainly by external head impacts poses significant health concerns globally. Understanding the mechanics behind TBI during head impacts is crucial for developing effective preventive and therapeutic strategies. In this study, the fluid–structure interaction within the system comprising the skull, brain, and the cerebrospinal fluid (CSF)-filled gap is investigated using finite element methods (FEM). Unlike most studies that model CSF as a solid, this research models CSF as a fluid, focusing on its fluid dynamics and their impact on brain tissue response to external head impacts. Additionally, this study is the first to model CSF as a non-Newtonian fluid, exploring its influence on injury metrics compared to a Newtonian CSF model. The results demonstrate significant pressure build-up and shear rate variations within the CSF due to impact. The model shows that maximum strain values are concentrated in the central regions of the brain tissue rather than at its interface with the CSF. Comparative analysis of the first and third principal strains shows that the tissue experiences twice as much compressive strain compared to tensile strain. Further, the comparison between Newtonian and non-Newtonian CSF models shows that the non-Newtonian model results in lower shear rates. This leads to a decrease in tissue strain, with a 4.3% reduction in the first principal strain and a 6.7% reduction in the third principal strain for the non-Newtonian CSF model. These findings underscore the importance of accurately modeling CSF properties to better understand TBI mechanisms.