Constitutive modeling of pia-arachnoid complex

Area of Science:

• Biomechanics
• Materials Science
• Neuroscience

Background:

• The pia-arachnoid complex (PAC) is crucial for brain mechanical response during impact.
• PAC exhibits complex, nonlinear viscoelastic and transversely isotropic material behaviors.
• Accurate modeling of the PAC is essential for understanding brain injury.

Purpose of the Study:

• To model the nonlinear viscoelastic, transversely isotropic material properties of the PAC.
• To incorporate collagen fiber strengthening within the meningeal plane using an exponential model.
• To provide data for improved computational brain models of the skull/brain interface.

Main Methods:

• Developed a constitutive model for the PAC using Mooney-Rivlin ground substance and exponential fiber strengthening.
• Determined material constants through in-plane tension, normal traction, and shear tests on bovine PAC specimens.
• Integrated experimental data to validate the proposed material model.

Main Results:

• Successfully modeled the nonlinear viscoelastic and transversely isotropic properties of the PAC.
• Quantified material constants essential for computational simulations.
• Demonstrated the feasibility of representing PAC behavior with the proposed model.

Conclusions:

• The developed model provides crucial information for accurately representing the PAC membrane.
• Improved PAC modeling enhances the skull/brain interface representation in computational models.
• This research advances the accuracy of finite element models for brain injury mechanism studies.