Discussion Forum

Hi,

I'm working on simulating:
1. the expansion of a cardiovascular stent and
2. the crimping of the same stent from its expanded to its delivery configuration.

I've been using as a starting point the application sample on stents atwww.comsol.com/model/plastic-deformation-during-the-expansion-of-a-biomedical-stent-2197, for version 5.1, basically imposing a displacement (radius as distance from the x-axis) as the stent expands, using symmetry boundary conditions at the edges of the stent (which make sense, since I'm modeling the unit cell that gets repeated multiple times to form the overall stent)

Although it works well, with small modifications,for some applications, it fails miserably and rather inexplicably for others. In particular:
1. it can model expansion of a unit cell making up 60 or 120 deg of the overall stent circumference, but immediately fails to converge for unit cells that are 90 or 180 deg.
2. more importantly, I cannot get it to model crimping the stent beyond maybe a reduction in radius of ~100um (out of 1-2mm). This is true regardless of whether I impose a pressure or a displacement, and doesn't seem to change as I refine the mesh and/or take smaller steps.

Any advice would be greatly appreciated!

Thanks,
Giovanni

p.s. I am attaching a 'typical versions' of the problematic models,
expanded_crimp_v000 which first slightly further enlarges and expanded stent, then tries to crimp it down to a smaller diameter