Simulation of three-point bending test of the silicon-coated nitinol bar

Abstract

Self-expanding intravascular stents made of nickel-titanium shape memory alloy (nitinol) serve to recover the lumen of vessels suffered from atherosclerotic stenosis. A novel drug-eluting stents are usually wrapping by a porous coating containing an antiproliferative drug around the stent struts. From the practical point of view, it is very important to understand the strength of the coating owing to the flexibility of the nitinol struts. In this paper, we study numerically the strength properties of a nitinol bar covered by a silicon coating, as a part of such a stent, under three-point flexural test using the method of movable cellular automata. The results show stages of the coating fracture as well as a periodic pattern of the cracks in the coating, which are confirmed by experimental evidence. The difference in computational and experimental results shows the way for future works on improving the model assumptions.