Finite element analysis of the mechanical performance of self-expanding endovascular stents made with new nickel-free superelastic β-titanium alloys

Tianyu Jia (1, 2, 3) , Dominique Guines (1, 2, 4) , Denis Laillé (1, 2, 3) , Lionel Leotoing (1, 2, 4) , Thierry Gloriant (1, 2, 3)

1 INSA Rennes - Institut National des Sciences Appliquées - Rennes
2 UR - Université de Rennes
3 ISCR - Institut des Sciences Chimiques de Rennes
4 LGCGM - Laboratoire de Génie Civil et Génie Mécanique

New Ni-free superelastic β-titanium alloys from the Ti–Zr–Nb–Sn system have been designed in this study to replace the NiTi alloy currently used for self-expanding endovascular stents. The simulation results, carried out by finite element analysis (FEA) on two β-type Ti–Zr–Nb–Sn alloys using a commonly used superelastic constitutive model, were in good agreement with the experimental uniaxial tension data. An ad-hoc self-expanding coronary stent was specifically designed for the present study. To assess the mechanical performance of the endovascular stents, a FEA framework of the stent deployed in the arterial system was established, and a simply cyclic bending loading was proposed. Six comparative simulations of three superelastic materials (including NiTi for comparison) and two arterial configurations were successfully conducted. The mechanical behaviours of the stents were analysed through stress localization, the increase in artery diameter, contact results, and distributions of mean and alternating strain. The simulation results show that the Ti–22Zr–11Nb–2Sn (at. %) alloy composition for the stent produces the largest contact area (9.92 mm2) and radial contact force (49.5 mN) on the inner surface of the plaque and a higher increase in the stenotic artery diameter (70 %) after three vascular bending cycles. Furthermore, the Ti–22Zr–11Nb–2Sn stent exhibited sufficient crimping capacity and reliable mechanical performance during deployment and cyclic bending, which could make it a suitable choice for self-expanding coronary stents. In this work, the implementation of finite element analysis has thus made it possible to propose a solid basis for the mechanical evaluation of these stents fabricated in new Ni-free superelastic β-Ti alloys.

Mots clés: Finite element analysis; Self-expanding stents; Superelastic property; Titanium alloys

Domaines: Matériaux

Tianyu Jia, Dominique Guines, Denis Laillé, Lionel Leotoing, Thierry Gloriant. Finite element analysis of the mechanical performance of self-expanding endovascular stents made with new nickel-free superelastic β-titanium alloys. Journal of the mechanical behavior of biomedical materials, 2024, Journal of the Mechanical Behavior of Biomedical Materials, 151, pp.106345. ⟨10.1016/j.jmbbm.2023.106345⟩. ⟨hal-04395165⟩