Extreme softness of brain matter in simple shear

Abstract

We show that porcine brain matter can be modelled accurately as a very soft rubber-like material using the Mooney-Rivlin strain energy function, up to strains as high as 60\%. This result followed from simple shear experiments performed on small rectangular fresh samples ($2.5$ cm${}^3$ and $1.1$ cm${}^3$) at quasi-static strain rates. They revealed a linear shear stress--shear strain relationship ($R^2>0.97$), characteristic of Mooney-Rivlin materials at large strains. We found that porcine brain matter is about 30 times less resistant to shear forces than a silicone gel. We also verified experimentally that brain matter exhibits the positive Poynting effect of nonlinear elasticity, and numerically that the stress and strain fields remain mostly homogeneous throughout the thickness of the samples in simple shear.

References in corpus (6)

• Mechanical Characterization of Brain Tissue in Compression at Dynamic Strain Rates
• Mechanical characterization of brain tissue in simple shear at dynamic strain rates
• Nonlinear Euler buckling
• Measuring the linear and nonlinear elastic properties of brain tissue with shear waves and inverse analysis
• Onset of Non-Linearity in the Elastic Bending of Blocks
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Cited by in corpus (6)

• Strain energy function for isotropic non-linear elastic incompressible solids with linear finite strain response in shear and torsion
• Stretch formulations and the Poynting effect in nonlinear elasticity
• Nonlinear modeling and characterization of ultrasoft silicone elastomers
• Shear shock formation in incompressible viscoelastic solids
• Modelling the non-linear viscoelastic behaviour of brain tissue in torsion
• Mechanics of poking a cyst