Fatigue Life Prediction And Reliability Analysis Of Vascular Stents

Peripheral arterial disease(PAD)is a kind of vascular lumen deformation and narrowing caused by atherosclerosis,and intermittent claudication and resting pain will occur along with the development of the disease.Stent intervention has become one of the important methods for the treatment of PAD,with little damage to human body and quick recovery.However,in the process of implantation and service,vascular stents will be affected by external loads such as stent release scale,plaque size,body position deformation and blood flow pulsation load,and the resulting damage may lead to stent deformation,collapse or fracture failure due to fatigue,thus reducing the service life and reliability of the stent.Therefore,the fatigue life and reliability of stents released into different blood vessels were studied to evaluate the safety of vascular stents.In view of the effects of stent release scale and narrowed blood vessels on fatigue life and reliability of lower limb arterial stents,finite element method was used to analyze four types of stents(Absolute Pro,Complete Fatigue strength and fatigue life of SE,E-luminexx-B and Pulsar-35)released at different release scales(80%,85%,90%)and vascular stenosis rates(0%,30%,50%,70%);The fatigue crack growth rate and reliability of Complete SE were analyzed by data processing method,and the fatigue failure mechanism of Complete SE was revealed.(1)By analyzing the fatigue performance of the four stents at different release scales and stenosis rates,it was found that the narrowed blood vessels had a significant impact on the fatigue performance of the stents,and the higher the stenosis rate had a greater impact on the fatigue strength of the stents.Under the same release and narrowing conditions,the fatigue strength of Pulsar-35 and E-luminexx-B scaffolds was the minimum,and the maximum.(2)Fatigue life of four scaffolds under different release scales and stenosis rates was predicted based on nominal stress method,and the influence of vessel diameter and shape on the fatigue life of scaffolds was revealed.The closed-loop structure of the Lower limb artery stent is the main factor affecting the life of the support at different release scales.At different stenosis rates,vessel stenosis rate is the main factor affecting stent life.(3)Based on Paris fatigue crack growth law of fracture mechanics,random variables were introduced to establish the fatigue crack growth rate,and the delay degradation model based on normal distribution and Poisson distribution random impact model were used to model the reliability of the support.The results show that the stress amplitude of the support in service is the main factor affecting the fatigue crack growth and reliability.Compared with the support size and release scale,the stenosis rate has the greatest influence on the crack growth rate and reliability of the support.This topic studied the fatigue life and reliability of lower limb artery stents under different release scales and stenosis rates,revealed the influence of stent geometry size and plaque size on its fatigue life and reliability,and provided a scientific reference for the research and development of lower limb artery stents and clinical selection.