A new constitutive model for multi-layered collagenous tissues.

Area of Science:

• Biomechanics
• Materials Science
• Biomedical Engineering

Background:

• Collagenous tissues, such as arterial walls, are complex multi-layered structures.
• Distinct fiber alignments characterize each layer, influencing overall mechanical properties.
• Existing constitutive models lack comprehensive representation of these multi-layered collagenous structures.

Purpose of the Study:

• To develop a novel constitutive model for multi-layered collagenous tissues.
• To incorporate anisotropic strain-energy functions reflecting material structure.
• To accurately represent the passive mechanical behavior dominated by elastin and collagen.

Main Methods:

• Utilized finite elasticity theory and an anisotropic strain-energy function.
• Modeled elastin using neo-Hookean material and collagen using a transversely isotropic exponential function.
• Ensured material stability through a polyconvex constitutive function.
• Employed the finite element method for simulations.

Main Results:

• The model incorporates five independent parameters with clear physical interpretations.
• Simulations of human femoral artery adventitia extension-inflation tests showed good agreement with experimental data.
• The model successfully captures the mechanical response of layered collagenous tissues.

Conclusions:

• The developed constitutive model provides a robust framework for analyzing multi-layered collagenous tissues.
• This approach enhances understanding of tissue mechanics in structures like aneurysms and aortas.
• The model's predictive capability was validated through experimental data, paving the way for further applications.