Impact of Corrosion on Tensile Properties of a Mg Alloy in a Finite Element Model of a Coronary Artery Stent Coupled with Geometry Optimization

Abstract

This study investigated the influence of corrosion-induced deterioration of the tensile properties of a Mg-1 wt.% Ca alloy on the performance of a coronary artery stent model fabricated using the alloy wire. Finite element analysis was used to determine the change in various characteristics of the model when immersed in a biosimulation aqueous solution (Earle’s Balanced Salt Solution). Results from tensile tests on wires fabricated from the alloy (non-treated versus ultrasound-assisted casting (US)) were used as input to a shape optimisation study of the stent, which aimed at reducing stent strut thickness and minimising corrosion-related parameters such as equivalent plastic strain and residual stress. For each of the characteristics, it was found that the US treatment produced a more desirable result compared to the stents modelled using non-treated material data; for example, the decrease in strut thickness, equivalent plastic strain, and residual stress were each markedly greater, while keeping the stent’s functionality. These results suggest that US-treated Mg-1 wt./wt.% Ca alloy may be promising for fabricating biodegradable coronary artery stents.