Abstract
The Cerebrospinal Fluid (CSF) can undergo shear deformations under head motions. Finite Element (FE) models, which are commonly used to simulate biomechanics of the brain, including traumatic brain injury, employ solid elements to represent the CSF. However, the limited number of elements paired with shear deformations in CSF can decrease the accuracy of their predictions. Large deformation problems can be accurately modelled using the mesh‐free Smoothed Particle Hydrodynamics (SPH) method, but there is limited previous work on using this method for modelling the CSF. Here we explored the stability and accuracy of key modelling parameters of an SPH model of the CSF when predicting relative brain/skull displacements in a simulation of an in vivo mild head impact in human. The Moving Least Squares (MLS) SPH formulation and Ogden rubber material model were found to be the most accurate and stable. The strain and strain rate in the brain differed across the SPH and FE models of CSF. The FE mesh anchored the gyri, preventing them from experiencing the level of strains seen in the in vivo brain experiments and predicted by the SPH model. Additionally, SPH showed higher levels of strains in the sulci compared to the FE model. However, tensile instability was found to be a key challenge of the SPH method, which needs to be addressed in future. Our study provides a detailed investigation of the use of SPH and shows its potential for improving the accuracy of computational models of brain biomechanics.
Highlights
This study evaluates the feasibility of using the mesh-free Smoothed Particle Hydrodynamics (SPH) method for modelling relative displacements in the Cerebrospinal Fluid (CSF) during head motions
The relative displacement between brain and skull plays a key role in transferring the external force, FIGURE 8 Comparison of total correlation analysis (CORA) scores for SPH to Finite Element (FE) model for each material model
By making comparisons to live human data, this study shows that the SPH method has the potential to improve the prediction of relative brain/skull displacement in computational models of brain biomechanics, when detailed anatomy of the brain, such as sulci and gyri, is incorporated in the model
Summary
Finite Element (FE) brain models are commonly used to assess brain biomechanics and the link between clinical pathology and brain deformation under head motion, for example, in traumatic brain injury (TBI).[1,2,3,4] Head motion can lead to relative displacement between the brain and skull, as seen in in vivo experiments in primate and human.[5,6,7]. The SPH formulation, inter-particle distance and smoothing length are studied to determine their effects on model predictions when compared with the in vivo data from a mild head impact experiment in human (Feng et al[7]). CSF material model and property choice can significantly influence the stability and accuracy of the simulation.[3,14,15,20] here the predictions of a large number of CSF material models incorporated in both SPH and FE representations of the CSF are determined. Predictions of brain/skull relative displacement and strain and strain rate distribution across the brain are compared to better understand the stability and accuracy of the SPH versus FE models of CSF
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