A strain-mediated corrosion model for bioabsorbable metallic stents.

Area of Science:

• Biomaterials Science
• Materials Engineering
• Computational Mechanics

Background:

• Degradable material modeling faces challenges in simulating strain-corrosion interactions.
• Magnesium alloys are promising for biodegradable implants but susceptible to corrosion.
• Understanding strain effects is crucial for predicting the lifespan of magnesium devices.

Purpose of the Study:

• To develop and validate a strain-mediated phenomenological corrosion model for magnesium alloy stents.
• To investigate the relationship between plastic strain and corrosion in WE43 magnesium alloy stents.
• To provide a predictive tool for optimizing the design and performance of magnesium implants.

Main Methods:

• Developed a strain-mediated phenomenological corrosion model using the finite element method (FEM).
• Calibrated the model using experimental data from corrosion tests on WE43 magnesium alloy stents.
• Simulated corrosion performance, including mass loss and radial stiffness reduction over time.

Main Results:

• The model accurately predicted experimentally observed plastic strain-mediated mass loss.
• The model captured the corrosion-induced reduction in radial stiffness due to plastic strain.
• This represents the first experimental calibration of such a model for a corroding magnesium stent.

Conclusions:

• Minimizing plastic strain during manufacture, deployment, and in-service is key to reducing corrosion rates.
• The developed model can guide future designs to enhance the mechanical integrity and longevity of magnesium devices.
• This work advances the understanding and prediction of corrosion in biodegradable metallic implants.