Finite Element Analysis Of The Mechaanical Behavior Of The Nitionl Stent Of Coronary Artery

The abnormal blood metabolism will induce the stenosis of coronaries luminal, consequently, the coronary atherosclerotic heart disease will happen, or simply coronary heart disease. With the advance of interventional therapeutic technique, the stent implantation becomes a mainstream way to treatment the coronary heart disease, and the stenting has three steps. Firstly stent is crimped into the micro-catheter, then along the bending blood vessel, last release when the stent arrived at the lesion location. Whether the design of stent is reasonable primarily depends on the main mechanical behavior of three steps above. NiTi has been used in interventional therapy widely because of its good biocompatibility. However, superelasticity and shape memory of the NiTi make the mechanical behavior of Nitinol stent complicated.In this paper, the deformation mechanism and mechanical behavior of nitinol stent are researched by finite element method. Firstly building the expanded plane model of stent by use of solidworks, secondly meshing by hypermesh, then carrying on the coordinate transformation by matlab, last the finite model of stent will be done by abaqus(“N” style and “S” style). Otherwise,the finite element method was used to study the mechanical behavior of stents,including the maximum strain,radial stiffness and longitudinal flexibility.The results show that the maximum equivalent uniaxial tension strain is within the elastic scope of NiTi when crimping or bending the Nitinol stent. The holding power is provided by the support body when the nitinol stent is released in the lesion location, and the style of support body(“N” style and “S” style) has no effect on the holding power. But the results show that the style of support body has effect on the longitudinal stretching behavior of the nitinol stent, the noteworthy difference was observed between “N” style and “S” style.The flexibility of nitinol stent is controlled by three factors: difference appears when bending of stent happens because of spiral distribution of the support body; compression energy of pressure zone increases because of self-contact; self-contact affects the bending behavior in all direction of stent. The bending behavior of stent was determined by its structural characteristics and the screw distribution of the connecting body and self contact make stents always showed anisotropic flexibility. shows that the stent has no difference in flexibility before the self contact occurs. Instead, the difference is obvious since the self contact has occured. In addition, the bending deformation is accompanied under the action of in-plane pure bending load with the out-of-plane deflection and torsion deformation around the axis,which In turn prove anisotropic flexibility of stents.The results of simulation analysis in this paper, to a certain extent, provide a theoretic basis and reference data for the design and mechanical behavior of the stent for the coronary heart disease.