Mechanical Behavior And Optimal Design Of Balloon-Dilated Coronary Stent

As people’s eating habits change,patients with vascular diseases become more and more younger and it becomes the main killers of good health.Due to the objective factors such as the existence of traditional methods of treatment can not be immediately effective,high risk,physical fitness requires higher and so on.Stent implantation has become the most effective treatment of cardio-cerebrovascular diseases and in clinical practice has been widely used.Stent implantation process has not only an impact on the structure,but also on the biomechanical properties of the scaffold itself and its blood flow characteristics in vivo.So the study of stent implantation process has been a hot spot of interventional therapy.This article is based on the scientific problem of postoperative stenosis,researching the modeling and structure optimization of the stent intervention process by the finite element method.The details are as follows:1.According to the biomechanical characteristics of stents involved in the process and the existence of a variety of nonlinear problems,this article mainly describes the basic numerical theory based on elastic-plastic mechanics.And then deduces the geometric nonlinearity and contact nonlinear numerical model.Finally on the basis of this,a variety of nonlinear parameters of the coronary stent intervention modeling process is set.2.According to the theory of elasto-plasticity and the related standard of stent,this article designs A stent,and the vascular parameters of human body in medical reports are used to establish the early,middle and high stenosis plaque and the curved blood vessel model with different curvatures.A finite element model of the interventional procedure to simulate 3 mm narrow curved vessels is developed.The coronary stent is used to simulate the dilatation of curved blood vessels with different stenosis rate and curvature.Compare A stent with B stent in structural performance and damage to blood vessels,doing experimental verification of A stent by building vitro test system.3.This paper first extracts the expansion of the model involved in the process of intervention after the stent is inserted to bend the blood vessel.Then a fluid-solid interaction analysis model is established and the material model of non-Newtonian fluid is constructed by the Transient Structural and CFX modules in ANSYS Workbench 15.0.Finally,carrying out the fluid-solid coupling calculation,and the calculation results are analyzed and studied.4.The result of fluid-solid coupling analysis which is used as the constraints of topological optimization and the minimization of flexibility as the optimization goal.Then a topology optimization system model is established by selecting the appropriate minimum size of a few members and using draft constraints.Optimize the structure of B stent link,and do contrastive analysis of topology optimization results under six minimum member sizes.