A visco-hyperelastic model of brain tissue incorporating both tension/compression asymmetry and volume compressibility

Abstract

The understanding of the mechanical behavior of the brain tissue is essential to prevent the occurrence of potential brain damage, such as traumatic brain injury. Recent experimental results showed that brain tissue exhibits significant tension/compression asymmetry. Due to the migration and diffusion of interstitial fluid, brain tissue also shows a moderate volume compressibility during loading. These mechanical characteristics have a strong impact on the deformation response of brain tissue. In this paper, a visco-hyperelastic constitutive model incorporating both tension/compression asymmetry and volume compressibility is proposed to describe the mechanical behavior of brain tissue under various loading modes. An Ogden-type model with the addition of a viscoelastic part is used to characterize the tension/compression asymmetry as well as the viscoelastic properties. Poisson’s ratio was introduced as a phenomenological index to represent the total volume change as well as the compressibility/recoverability. The mechanical responses of brain tissue under uniaxial tension, unconfined compression, stress relaxation, and cyclic compression were reproduced with a good capture of the tension/compression asymmetry, volume compressibility, significant viscoelastic properties, and cyclic hysteresis behaviors. The good agreement with the experimental data implies that the proposed model has a strong capability to describe the complex mechanical performance of brain tissue under a variety of loading conditions.