Numerical Analysis of Mechanical Phenomena in Coronary Stent Made of Titanium Alloy Ti-13Nb-13Zr

Using the finite element method, this study determined mechanical characteristics of slotted-tube stents. The numerical calculations were carried out using ADINA v.8.8 software. Three models with different number of segments were used. The analysis was carried out for the titanium-matrix alloys Ti-13Nb-13Zr. Assuming the actual conditions of stent implantation, the stent is expected to expand to the diameter of 3.0 mm i.e. until it reaches the internal diameter of a healthy coronary vessel. The effect of the stent geometry was analysed, with emphasis on examination of the effect of key mechanical phenomena such as expansion pressure and suitable level of stress and plastic strain in stents. Analysis of the degree of foreshortening and dogboning after stent expansion was also carried out. The following assumptions were adopted in order to determine mechanical properties of stents: implantation at low expansion pressure, limitation of foreshortening ≤ 2%, low increase in the implant diameter in the beginning and at the end of the stent (dogboning effect).