Simulation And Experimental Investigation Into Mechanical Behaviors Of Plla Stents During Crimping And Expanding

Coronary stent implantation is the main method to treat coronary heart disease.The crimped stent is implanted into the diseased vessel,and then the stent expanded to support the narrow vessel restoring blood circulation.At present,the new generation of biodegradable polymer stent solves the problems caused by the permanent implantation of metal stents,but its mechanical properties are insufficient,and the greater wall thickness of the polymer stent increases the risk of restenosis.The stent undergoes large deformation during crimping and expanding,affecting the mechanical properties of the stent.In this paper,the mechanical behaviors of the biodegradable thin-walled polymer coronary stent in the process of crimping and expanding are studied by combining experiments and simulations.The main research methods and results are as follows(1)Based on the tensile test data,a anisotropy polymer material model for coronary stents was established.To study the properties of Poly-L-lactic acid(PLLA)used in this study,tensile tests were performed on the axial and circumferential tensile specimens made from PLLA pipe.The experimental results show that the PLLA pipe has anisotropy.An anisotropic material model of PLLA material was established based on the tensile experiment,and the accuracy of the model was verified by simulating the tensile experiment.(2)The numerical simulation and experiment about the crimping and expanding process of thin-walled polymer coronary stents were completed.By improve the technique of stent crimping and expanding process,the thin-walled PLLA stent can be crimped without collapsed.Based on the above anisotropic polymer material model,a numerical simulation model of the stent crimping and expanding process is established.By analyzing the experimental and simulation results,the mechanical behaviors of the PLLA stent during implantation were studied,and the accuracy of the simulation model was verified.(3)The radial force test and simulation of degradable thin-walled polymer stent was completed.Using radial force tester and numerical simulation respectively,the radial force test was carried out on the thin-wall polymer stent after crimping and expanding to evaluate the mechanical properties of the stent.The results show that the thin-walled polymer stent used in this paper has sufficient radial support.The simulation results are basically consistent with the experimental results,quantitatively verifying the accuracy of the simulation model,and provide support for further optimization of the stent.