| Vascular stenting is the main treatment for cardiovascular disease.In clinical practice,permanent stents are mainly used,but the implantation of permanent stents does not work once and for all.Biodegradable stents become a new generation of stents.Among them,zinc alloy material has good biocompatibility and good material strength.The new degradable zinc alloy has become a research hotspot for degradable scaffold materials.This paper studies the support performance and degradation performance of the new type zinc alloy stent,and provides a scientific reference for the design and application of the new zinc alloy stent.Using a three-dimensional modeling method,an idealized stenotic vascular model and an I-type connecting tendon stent were constructed.The ABAQUS finite element analysis software was used to simulate the expansion of stents in idealized stenotic vessels with a stenosis rate of 50% in both calcified and non-calcified plaque types.The sample preparation was performed.The sample was cleaned and weighed and placed in a circulatory pulsation lab bench for in vitro corrosion simulation.After sampling,processing,weighing,and data processing.According to the continuous damage formula provided in the literature,prepare the ABAQUS Kvuscc subroutine for stress corrosion,and set the corresponding main program to call the subroutine in the ABAQUS/Explicit analysis to complete the entire stress corrosion simulation process.A simple zinc alloy specimen was constructed to simulate the uniaxial tensile process of the specimen,and the post-processing results were extracted after stress analysis.The stress corrosion process was simulated.In the calcified and non-calcified models of plaque material properties,the maximum stress during the stent expansion phase was 433.4 MPa and 432.4 MPa,and the maximum stress values during the rebound phase were 266.1 MPa and 259.4 MPa,respectively;the stent bone rate was 44.5 respectively.%,33.3%,residual stenosis rate of 40.8%,30.2%.In the cyclic pulsation table in vitro corrosion experiment,the mass loss of zinc alloy specimens was weighed in different time periods.The loss volume was calculated based on the lost mass and the density of the material itself.The corrosion rates at different times were calculated to be 0-14 days corrosion rate: 0.083 mm/y,15-28 days corrosion rate: 0.174 mm/y,29-42 days corrosion rate: 0.310 mm/y.Experiments have shown that the corrosion rate of this material gradually increases in 0-42 days.In ABAQUS,the uniaxial stress tensile model of the zinc alloy specimen was simulated,and the tensile stress was kept constant after 0 gradually increasing to 260 MPa.When the equivalent stress is less than the threshold(50% of the yield stress),no stress corrosion occurs when the model stress is 110 MPa.When the equivalent stress is equal to the threshold,the model begins to stress corrosion,the stress at this time is 110 MPa,and stress corrosion begins to occur.After the stress reached 260 MPa,the model continued to undergo stress corrosion until the tensile part of the model completely disappeared.This study shows that the new type of zinc alloy stent can be applied to the treatment of stenotic carotid arteries of different lesion types,providing guidance and reference for the development of zinc alloy stents.The degradation rates of the new zinc alloys obtained in different time periods can provide experimental basis for subsequent studies.A stress corrosion subroutine based on the continuous damage model of a new type of zinc alloy can be used to calculate the stress corrosion results of a zinc alloy material under uniaxial tension and to simulate the stress corrosion process of a new type of zinc alloy for the new type zinc alloy stent in a stenosis vessel.Stress corrosion in the foundation provides a numerical simulation. |
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