A finite element approach for gastrointestinal tissue mechanics

Area of Science:

• Biomechanics
• Biomedical Engineering
• Computational Mechanics

Background:

• Gastrointestinal (GI) soft tissues exhibit complex nonlinear, rate- and time-dependent stress-strain behavior crucial for organ function.
• Existing constitutive relations alone are insufficient for analyzing organ-level biomechanics under complex conditions.
• A finite element (FE) implementation is necessary for refined mechanical analysis of GI tissues.

Purpose of the Study:

• To develop and validate a finite element (FE) implementation of a finite nonlinear hyperviscoelastic model for soft biological tissues.
• To propose a method for constructing a residually stressed FE model to investigate the impact of residual stresses on GI mechanics.
• To analyze the biomechanical properties of gastrointestinal tissue.

Main Methods:

• Developed a finite element (FE) implementation of a finite nonlinear hyperviscoelastic model.
• Validated the FE model against analytical solutions for a standard linear solid.
• Recreated experimental observations on animal tissue strips using the FE model.
• Proposed and implemented a method for constructing residually stressed FE models.

Main Results:

• The FE formulation successfully captured the nonlinear mechanical properties of soft tissues.
• Validation against analytical solutions and experimental data confirmed the model's accuracy.
• The residually stressed FE model demonstrated that residual stresses reduce stress concentrations and gradients in the GI wall.
• The model provides a tool for examining the consequences of residual stresses on GI mechanics.

Conclusions:

• The developed FE model accurately represents the biomechanical properties of GI soft tissues.
• Incorporating residual stresses into FE models is crucial for a comprehensive understanding of GI mechanics.
• The findings suggest that residual stresses play a protective role by mitigating stress concentrations in the GI wall.