Finite element analysis of the effect of different stress levels on the degradation of the stent
Objective Establish a stent degradation model with multiple factors to explore the effects of different stress levels on degradable vascular stents ' degradation behavior and degradation performance. Methods Based on the continuous damage mechanics principle,the stents' mechanical strength and geometric changes in the degradation were simulated by setting corrosion properties and material properties for the independent elements under the finite element framework,then a stent degradation model of uniform corrosion, stress corrosion,and pitting corrosion was established. The stent was expanded to 1. 05,1. 1,and 1. 2 times the vessel diameter,respectively,to provide different stress levels for the stent,and the degradation process under three different conditions was numerically simulated. The stents ' shape, mass loss rate, and time during degradation were analyzed. Results The stress level of stents after deployment significantly affects its degradation performance with the increase of expansion ratio,the fracture time of the stent under three stress levels was 0. 95,0. 82,and 0. 78,and the mass loss rate at fracture was 73％, 63％, and 60％. During the degradation, the number of elements removed mainly by stress corrosion was 112, 125, and 139, respectively, and the fraction of stress corrosion as the dominant factor time was 0. 93,0. 82,and 0. 78,respectively. The fraction of vascular collapse time was 0. 83, 0. 72, and 0. 68, respectively. Vascular collapse occurs before the stent loses its mechanical integrity. Conclusions Choosing an appropriate expansion ratio for biodegradable stents have a significant impact on the well treatment effect. Although a high expansion ratio could better maintain lumen patency,it also increases local stress corrosion by increasing the stress level at the corolla,thereby shortening the degradation time of the stent and making it more prone to non-uniform degradation.
biodegradable vascular stentexpansion ratiosupporting performancestress corrosionfinite element analysis
万方数据
维普
