Finite element simulation of stent and balloon interaction

A nonlinear finite element simulation was performed to analyse the interaction between the balloon and slotted tube stent during stent delivery. The analysis was performed using finite element packages LS-DYNA for solution of the problem and ANSYS (version 5.6) as a pre- and post-processor. Finite element models with different material properties were created for the balloon and slotted tube stent. Both ends of the balloon were assumed to be fully tethered and hence only the expansion in radial direction was allowed, whereas the stent had free boundary conditions and was allowed to move in any direction. A surface to surface contact algorithm approach was used in order to cope with the nonlinear contact problem between the two component surfaces. Material nonlinearities were accounted for in the analysis. The stent was meshed with tetrahedral elements to properly model the geometry and a bi-linear elasto-plastic material model was assumed for the stent material. A hyperelastic material model was assumed for the balloon. In this investigation, the pressure was applied as a surface load on the inner surface of the balloon. Pressure load provided the force which caused the dilation of the stent. The displacement and stress distributions over the stent were computed and analysed. The deformation characteristics of the stent and localised stress region under application of internal pressure are presented.