Analysis Of Hemodynamics And Degradation Characteristics Of Vascular Stent

With the increasing aging population,cardiovascular disease has become the primary threat to human health.Under the unremitting efforts of researchers,great achievements have been made in the development of vascular stents.However,few studies have been focused on the hemodynamic characteristics of blood during stent implantation and the interaction of the "vessel-plaque-scaffold" system in the degradation process.In this thesis,the hemodynamic characteristics and degradation characteristics of degradable magnesium alloy scaffold are studied by numerical simulation.The contents are as follows:(1)The process of stent implantation in the combined model is analyzed,and the results show that the self-designed magnesium alloy stent has good mechanical properties,all indexes are within a safe range,and plaque blockage is eliminated after stent implantation;The (?) inflexion points in the support structure play a major role in the radial support strength.(2)The process of stent implantation in the blood environment is analyzed and compared with the situation without implants.The results show that: the blood flow rate inside the blood vessel,the pressure and the shear stress on the inner surface of the blood vessel wall are consistent with the change of the inlet blood flow rate;Stent and balloon can affect the blood flow in the process of implantation,and there is circumfluence phenomenon at the same time;With the continuous expansion of the stent and balloon,the maximum and gradient of the pressure and shear stress on the inner surface of the vessel wall rise sharply,and the blood flow is greatly hindered.(3)The degradation process of magnesium alloy scaffold during service is analyzed.The results show that the interaction between vascular wall,plaque and scaffold lead to the stress in the scaffold decreasing first and then increasing;When degradation occurs,the (?) inflexion point of the scaffold will have a greater impact on the radial deformation of the scaffold compared with other structures.(4)The stability of magnesium alloy scaffold is analyzed,and the buckling characteristics before and after degradation are compared.The results show that the degradation process led to stability breakage of the scaffolds,and the critical load of the scaffolds is greatly reduced after degradation.At the same time,the range of stress variation from buckling to complete failure is reduced because of the degradation.