Coupled electro-mechanical models of fiber-distributed active tissues.

Area of Science:

• Biophysics
• Materials Science
• Computational Mechanics

Background:

• Existing models for fiber-reinforced tissues often rely on complex numerical methods or simplified tensor representations.
• The active behavior of these tissues is influenced by external stimuli like electric fields, necessitating models that capture this electromechanical coupling.

Purpose of the Study:

• To develop a novel constitutive model for stochastically distributed fiber-reinforced tissues.
• To accurately predict both passive and active mechanical responses, particularly focusing on electromechanical coupling.
• To offer a computationally efficient alternative to existing modeling approaches.

Main Methods:

• A second-order approximation of strain energy density for passive behavior.
• Extension of Helmholtz free energy with a directional active potential for active behavior.
• Utilizing averaged structure tensors (second and fourth order) to characterize mechanical properties.

Main Results:

• The model explicitly derives active stress and constitutive tensors dependent on the same structure tensors as the passive response.
• Predicted active anisotropy arises directly from the stochastic fiber distribution.
• Model predictions for passive and active behaviors under biaxial testing were presented and compared with experimental data.

Conclusions:

• The developed constitutive model provides a robust framework for analyzing electromechanically coupled behaviors in fiber-reinforced tissues.
• The use of second-order approximations offers a balance between accuracy and computational efficiency.
• The model successfully captures active anisotropy and its dependence on fiber distribution.