Poynting effect of brain matter in torsion

Abstract

We investigate experimentally and model theoretically the mechanical behaviour of brain matter in torsion. Using a strain-controlled rheometer we perform torsion tests on fresh porcine brain samples. We quantify the torque and the normal force required to twist a cylindrical sample at constant twist rate. Data fitting gives a mean value for the shear modulus μ = 900 $\pm$ 312 Pa and for the second Mooney-Rivlin parameter $c_2$ = 297 $\pm$ 189 Pa, indicative of extreme softness. Our results show that brain always displays a positive Poynting effect; in other words, it expands in the direction perpendicular to the plane of twisting. We validate the experiments with Finite Element simulations and show that when a human head experiences a twisting motion in the horizontal plane, the brain can experience large forces in the axial direction.

arXiv comment6 pages, 6 figures, 2 tables

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
• Extreme softness of brain matter in simple shear
• Inhomogeneous Deformation of Brain Tissue During Tension Tests
• Temperature Effects on Brain Tissue in Compression
• Strain energy function for isotropic non-linear elastic incompressible solids with linear finite strain response in shear and torsion

Cited by in corpus (5)

• Surface tension controls the onset of gyrification in brain organoids
• Canceling the elastic Poynting effect with geometry
• The Poynting effect
• Modelling the non-linear viscoelastic behaviour of brain tissue in torsion
• Self-Consistent Fourier-Tschebyshev Representations of the First Normal Stress Difference in Large Amplitude Oscillatory Shear