Transient Mg-Stent Expansion by Finite Element Method

The percutaneous transluminal coronary angioplasty (PTCA) assisted with stenting procedure has become a primary treatment to coronary heart disease. The expansion behavior of the cardiovascular stent is important for design and development and the finite element method (FEM) is an efficient way to study it. Two common FEM models are currently used to simulate the cardiovascular stent. In the first, pressure is directly applied to the inner stent, whereas in the second model, the balloon simulated as a shell. In our research pressure is directly applied to the inner surface of the stent. In this paper, a 3D geometrical model of the new heart-shaped- cell stent is studied. The material of the stent is magnesium Alloy. The dimensions of the stent are, length 7mm, 1.3mm outer diameter, cross sectional width and length are 0.08mm respectively. The stent structure is meshed by the 20 node solid 186 tetra mesh. The boundary condition applied at the cross sectional nodes of the stent structure. To ensure the coronary stent model is properly constrained symmetrically. All nodes limiting the displacement in the Y-direction, but does not hinder its direction in the X and Z displacement.  The transient load is applied in the inner surface of the stent. Nonlinear transient analysis is carried out by using commercial finite element package ANSYS.

It is reported that finite element method (FEM) applied to simulate the transient expansion process of magnesium stent system and to obtain the mechanical properties. Six mechanical properties are studied by mathematical modeling with determination of: (1) stent deployment pressure, (2) the intrinsic elastic recoil of the material used,(3) the stent foreshortening, (4) the stent coverage area, (5) the stent flexibility, and (6) the stress maps. These results show the potential application and implanted behavior of the Magnesium stent design and material.