Best Practices for Stent Analysis with Abaqus (1)

Element Selection:

As stent is loaded dominantly in bending,

 the reduced-integration (C3D8R) and 

incompatible mode element (C3D8I) are more appropriate for the stent analysis. For C3D8R, it is computational inexpensive as only one integration point per element. However, due to hourglassing issue, at least four elements through the thickness is required to mitigate the potential problems. There is no particular limitation for C3D8I. But this type of element is more expensive than C3D8. Since t

he maximum stress/strain of a stent usually lies on the stent surface due to bending-dominated loading conditions and material calculations are carried out at the integration points, it is better to overlay membrane elements on the free surface of a reduced-integration element model. This will add integration points on the surface and reduce the error caused by extrapolation. As pointed by a study conducted at Dassualt Systemes, 

"models with C3D8R elements alone (i.e., without overlaid membranes) underestimate the peak maximum principal stress unless a very fine mesh is used, which could result in overestimation of the fatigue safety factor and fatigue life. With membrane overlay, the peak stress is overestimated with the coarsest mesh studied. The overestimation is reduced significantly with a finer mesh"

Reference: Abaqus Answer 4516