Mathematical models are often employed to better understand the internal dynamics of the human head under impact loading. Mathematical models require accurate material properties of the brain in order to make accurate predictions. The objective of this study was to determine a specific material model for the brain tissue by examining different material laws and determining respective constants. Five finite element models were developed to simulate the three material constitutive laws, namely the hyperelastic rubber, viscoelastic Ogden rubber, and Mooney-Rivlin rubber, proposed by the three research groups using an explicit finite element analysis package LS-DYNA to simulate their respective experimental setups and compare model predictions against experimental results. Using the results from this study, a single set of material constants and the most suitable material model to simulate all three experimental setups was proposed.
The proposed material model (viscoelastic Ogden rubber) was compared with the linear viscoelastic rubber used previously by Zhang et al. (2001). The proposed material model predicted higher stress when compared to linear viscoelastic model. The study also involved implementation of the proposed material constants for the Ogden rubber material law using a cubic model and a spherical model which represent a simplified skull/brain structure and compare model predicted responses with those predicted by the linear viscoelastic material model used by Zhang et al. (2001). The strain predicted by both simplified models using the proposed material law was found to be high in the regions away from the simulated skull and considerably higher strain in the regions near the skull.
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