Nickel-Titanium peripheral stents: Which is the best criterion for the multi-axial fatigue strength assessment?

Abstract

Ni-Ti stents fatigue strength assessment requires a multi-factorial complex integration of applied loads, material and design and is of increasing interest. In this work, a coupled experimental-numerical method for the multi-axial fatigue strength assessment is proposed and verified for two different stent geometries that resemble commercial products. Particular attention was paid to the identification of the material fatigue limit curve. The common approach for the Ni-Ti stents fatigue assessment based on the von Mises yield criterion was proven unsuitable for a realistic fatigue strength assessment. On the other hand, critical plane-based criteria were more representative of the experimental outcomes regardless of stent design.

Keywords: Fatigue criterion; Multi-axial fatigue; Ni–Ti; Peripheral stent; Shape-memory device.