A computational study of invariant I5 in a nearly incompressible transversely isotropic model for white matter

Yuan Feng; Suhao Qiu; Xiaolong Xia; Songbai Ji; Chung-Hao Lee

doi:10.1016/j.jbiomech.2017.03.025

A computational study of invariant I₅ in a nearly incompressible transversely isotropic model for white matter

J Biomech. 2017 May 24:57:146-151. doi: 10.1016/j.jbiomech.2017.03.025. Epub 2017 Apr 9.

Authors

Yuan Feng¹, Suhao Qiu², Xiaolong Xia², Songbai Ji³, Chung-Hao Lee⁴

Affiliations

¹ Center for Molecular Imaging and Nuclear Medicine, School of Radiological and Interdisciplinary Sciences (RAD-X), Soochow University, Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Suzhou, Jiangsu 215123, China; School of Mechanical and Electronic Engineering, Soochow University, Suzhou, Jiangsu 215021, China. Electronic address: fengyuan@suda.edu.cn.
² Center for Molecular Imaging and Nuclear Medicine, School of Radiological and Interdisciplinary Sciences (RAD-X), Soochow University, Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Suzhou, Jiangsu 215123, China; School of Electronic and Information Engineering, Soochow University, Suzhou, Jiangsu 215021, China.
³ Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA.
⁴ School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA; Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX 78712, USA.

Abstract

The aligned axonal fiber bundles in white matter make it suitable to be modeled as a transversely isotropic material. Recent experimental studies have shown that a minimal form, nearly incompressible transversely isotropic (MITI) material model, is capable of describing mechanical anisotropy of white matter. Here, we used a finite element (FE) computational approach to demonstrate the significance of the fifth invariant (I₅) when modeling the anisotropic behavior of white matter in the large-strain regime. We first implemented and validated the MITI model in an FE simulation framework for large deformations. Next, we applied the model to a plate-hole structural problem to highlight the significance of the invariant I₅ by comparing with the standard fiber reinforcement (SFR) model. We also compared the two models by fitting the experiment data of asymmetric indentation, shear test, and uniaxial stretch of white matter. Our results demonstrated the significance of I₅ in describing shear deformation/anisotropy, and illustrated the potential of the MITI model to characterize transversely isotropic white matter tissues in the large-strain regime.

Keywords: Biomechanics; Constitutive modeling of biomaterials; Finite element methods; Tissue mechanics; White matter.

MeSH terms

Anisotropy
Computer Simulation
Finite Element Analysis
Humans
Models, Biological*
Stress, Mechanical
White Matter / physiology*

Abstract

MeSH terms

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