Analysis And Optimization Of Mechanical Properties Of Two-component Degradable Ureteral Stent

With the development and application of biodegradable materials,the research and application of biodegradable ureteral stents have been put on the agenda more and more.On the basis of the drainage effect of traditional stents,the biodegradable ureteral stents can avoid further injury caused by secondary surgery.Due to the inevitable extrusion and stretching of the support tube in the process of using the support tube,the mechanical properties of the support tube are also put forward higher requirements.In the process of preparing the stent tube,PGA and PGLA materials were selected to make the two-component degradable ureteral stent tube through physical test and other experiments on degradable materials.The traditional mechanical properties test is time-consuming,heavy workload and high cost.Therefore,this paper firstly conducts mechanism modeling of support tube,and uses intelligent optimization algorithm to optimize model parameters,so as to make the mechanism model more accurate.In order to more intuitive specific stent was simulated process of compression and tensile stents tube in each point and the size of bearing force and the stress distribution cloud,choose the method of finite element modeling to better analyze the mechanical properties of scaffold tube,and through the contrast test of different structure parameters to explore the change of the structure parameters effect the performance of the stent was compressed.In order to explore the optimal mechanical properties of stent tubes,this paper mainly carried out the following three aspects of research:（1）The mechanism model of the compression process of the two-component degradable ureteral stent was established and analyzed,and the improved whale optimization algorithm was used to optimize the model,and a set of parameters to make the model have the optimal ratio were found.Firstly,based on the prepared scaffolds,the kinematic analysis of the scaffolds in the compression process was carried out from the macro and micro aspects,and the mechanism model and the objective function of optimization were established.Secondly,nonlinear control parameters and adaptive weights are added into the whale optimization algorithm to improve the global search ability of the algorithm.Finally,the improved whale optimization algorithm is used to optimize the support tube model and improve the accuracy of the compression mechanism model.（2）The finite element model of the compression process of the two-component degradable ureteral stent was established and analyzed,and the control variables of different structural parameters were compared to further analyze the influence of different structural parameters on the compressive mechanical properties of the stent.Firstly,through the mathematical formula derivation and structure analysis of the bracket tube geometric model,the three-dimensional space bracket tube model with 1:1 equal ratio is improved and established.Secondly,the stress distribution cloud diagram and stress curve on each unit of the support tube are calculated by simulation experiment.Finally,the influence of yarn friction coefficient,yarn radius and braiding Angle on the compression performance of the support tube was summarized by controlling a single variable.（3）The mechanism model and finite element model of the stretching process of the twocomponent degradable ureteral stent were established and analyzed.Firstly,the tensile mechanism model was established,and the optimization algorithm was further improved to improve the accuracy of the tensile mechanism model.Secondly,the finite element model is used to simulate the tensile process of the support tube,and the influence of the structural parameters on the mechanical properties of the support tube during the tensile process is analyzed.