Temperature and Frequency Dependent Viscoelasticity of Brain Tissue under Dynamic Shear Loading

In traffic crashes, mechanical loads are applied within milliseconds, resembling frequency sweeps in dynamic mechanical testing. While brain mechanics have been widely studied, the effect of temperature on brain tissue’s mechanical response remains unclear, with limited and inconsistent findings. Additionally, few studies have examined how temperature affects brain tissue model parameters, which could provide a more detailed mechanical analysis of such effects. To address this, we conducted dynamic shear experiments on bovine brain tissue within the linear viscoelastic region and developed a generalized Maxwell model. Our primary objective was to investigate the influence of temperature on the dynamic properties of brain tissue, focusing on temperature-dependent changes in viscoelastic parameters, while also assessing frequency effects. Results showed that storage and loss moduli increased with frequency at all tested temperatures (5°C, 25°C, and 35°C), indicating stronger elastic responses and greater energy dissipation at higher frequencies. Both moduli decreased with rising temperature, demonstrating a softening effect, with more pronounced differences at 5°C. Dynamic viscosity was higher at lower temperatures, especially at low frequencies, but differences diminished at higher frequencies. The generalized Maxwell model revealed that absolute parameters decreased with temperature, while normalized parameters showed increased elasticity at higher temperatures and stronger viscosity at lower temperatures. These findings provide detailed insights into the temperature-dependent mechanical properties of brain tissue, enhancing computational simulations of brain behavior under varying thermal conditions and advancing research on brain injuries and biomechanical studies.