Inhomogeneous deformation of brain tissue during tension tests

Mechanical characterization of brain tissue has been investigated extensively by various research groups over the past 50 years. These properties are particularly important for modeling 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 (μ = 4395.0 Pa, α = −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.

► We show what dimensions of tensile test specimens ensure homogeneous deformations.
► Cylindrical specimens of diameter/thickness ratio no larger than 10:10 are suitable.
► New Ogden parameters for low dynamic conditions for brain tissue are established.
► For a strain rate of 30/s, the one-term Ogden parameters are μ = 4395 Pa and α = −2.8.
► These parameters can be used to simulate the dynamic response of brain tissue.