Simulation and Experimental Investigation into Mechanical Behaviors of PLLA Stents during Deployment

The biodegradable Poly-L-lactic acid (PLLA) stents are widely used for curing coronary heart disease. In this paper, the mechanical behaviors of an independently developed thin-walled PLLA stent during deployment were investigated by finite element method and experiment. First, tensile experiments were performed on PLLA material for setting an anisotropic material model. This model can capture the different properties of the PLLA tubing in the axial and circumferential directions, improving the accuracy of the simulation of stents. Then the deployment process of stent including crimping and expanding was simulated and the related experiments were carried out. The simulation results had a good agreement with experiments, showing the deformation and stress distribution of the thin-walled PLLA stent. These results indicated that the technology of thin-walled PLLA stent deployment process was feasible without stent collapse. In addition, the simulation results can predict the weak position of the thin-walled PLLA stent, which facilitates the subsequent optimization of the stent geometry.