Inhomogeneous Deformation of Brain Tissue During Tension Tests

TL;DR

This study develops a high-rate tension device and investigates inhomogeneous deformation in brain tissue, providing new insights into how specimen geometry affects mechanical testing outcomes relevant to traumatic brain injury modeling.

Contribution

The paper introduces a novel high-rate tension device and combines experimental and numerical methods to analyze inhomogeneous deformation in brain tissue during tension tests.

Findings

Inhomogeneous deformation depends on specimen thickness and aspect ratio.

Derived Ogden model parameters for brain tissue at high strain rates.

Recommended specimen aspect ratio to minimize deformation effects.

Abstract

Mechanical characterization of brain tissue has been investigated extensively by various research groups over the past fifty years. These properties are particularly important for modelling Traumatic Brain Injury (TBI). In this research, we present the design and calibration of a High Rate Tension Device (HRTD) capable of performing tests up to a maximum strain rate of 90/s. We use experimental and numerical methods to investigate the effects of inhomogeneous deformation of porcine brain tissue during tension at different specimen thicknesses (4.0-14.0 mm), by performing tension tests at a strain rate of 30/s. One-term Ogden material parameters (mu = 4395.0 Pa, alpha = -2.8) were derived by performing an inverse finite element analysis to model all experimental data. A similar procedure was adopted to determine Young's modulus (E= 11200 Pa) of the linear elastic regime. Based on this analysis, brain specimens of aspect ratio (diameter/thickness) S < 1.0 are required to minimise the effects of inhomogeneous deformation during tension tests.