A Computational Modelling of the Mechanical Performance of a Bioabsorbable Stent Undergoing Cyclic Loading

In order to address new challenges that arise in the degradation behavior of absorbable metal stents (AMSs) in vivo, new modelling and simulation are presented in this study. A dynamic corrosion model (Model 1) considering uniform corrosion, stress corrosion mechanisms and dynamic cyclic pulse loading was proposed to simulate the stent degradation based on Continuum Damage Mechanics (CDM). A control group (Model 2) was established which only considered the mechanisms of uniform and stress corrosion. The time of stent degraded completely in Model 1 was set as a normalized time unit (100t) to illustrate the results. With the increase of time, the mass and supporting performance of the stent decreased, especially at 10t to 20t. The average von Mises Stress of the stent in the Model 1 decreases from 86.19 MPa to 48.65 MPa roughly at 5t to15t, while the average von Mises Stress in Model 2 decreases from 87.12 MPa to 50 MPa. The mass loss ratio of stents in Model 1 is always higher than that in Model 2, and the relative error of the mass loss ratio reached 14.3% at 20t. The results showed that the corrosion occurs at first in the stent struts with the highest von Mises stress. In addition, the dynamic cyclic pulse loading accelerated the degradation rate and the supporting performance loss of stent. These modelling and simulation techniques may provide new insights to in vivo AMS performance.