Fluid-solid interaction in the rate-dependent failure of brain tissue and biomimicking gels

TL;DR

This study explores how the rate of cutting affects brain tissue fracture properties, combining experiments and a fluid-structure interaction model to reveal rate-dependent toughening due to fluid-solid interactions.

Contribution

It introduces a novel poro-hyperelastic model for rate-dependent fracture in soft materials, validated by experiments on brain tissue and biomimicking gels.

Findings

Higher cutting rates increase tissue toughness.

Fluid-solid interactions dissipate more energy at higher rates.

The model accurately predicts experimental fracture behavior.

Abstract

Brain tissue is a heterogeneous material, constituted by a soft matrix filled with cerebrospinal fluid. The interactions between, and the complexity of each of these components are responsible for the non-linear rate-dependent behaviour that characterizes what is one of the most complex tissue in nature. Here, we investigate the influence of the cutting rate on the fracture properties of brain, through wire cutting experiments. We also present a model for the rate-dependent behaviour of fracture propagation in soft materials, which comprises the effects of fluid interaction through a poro-hyperelastic formulation. The method is developed in the framework of finite strain continuum mechanics, implemented in a commercial finite element code, and applied to the case of an edge-crack remotely loaded by a controlled displacement. Experimental and numerical results both show a toughening effect with increasing rates, which is linked to the energy dissipated by the fluid-solid interactions in the process zone ahead of the crack.