On the Importance of Including Cohesive Zone Models in Modelling Mixed-Mode Aneurysm Rupture.

Area of Science:

• Biomedical Engineering
• Computational Mechanics
• Cardiovascular Research

Background:

• The precise mechanism of abdominal aortic aneurysm (AAA) rupture is not fully understood.
• Current models often overlook the layered, stepwise failure of arterial tissue.
• Experimental evidence points to fibrous delamination and kinking as critical failure modes.

Purpose of the Study:

• To investigate the role of interlayer tractions and delamination in AAA rupture.
• To explore how anatomical features influence the likelihood of delamination.
• To compare stress and delamination locations in patient-specific AAA models.

Main Methods:

• Utilized cohesive zone models to simulate interlayer delamination alongside von Mises stress.
• Conducted parametric studies on AAA anatomical features influencing interlayer traction.
• Developed and analyzed three patient-specific AAA finite element models from CT scans.

Main Results:

• Peak von Mises stress and tangential traction often coincide, but not always.
• For short, high-curvature aneurysms (L/R < 2) and those with intraluminal thrombus, peak stress and traction locations diverge.
• Patient-specific models confirmed that peak stress does not always correlate with the site of interlayer delamination.

Conclusions:

• Interlayer delamination is a critical factor in AAA rupture, not fully captured by stress alone.
• Cohesive zone models offer a more mechanistically grounded approach to simulating AAA failure.
• Integrating cohesive zone models into finite element analysis can enhance in-silico prediction of AAA ruptures.