Stent simulation with Abaqus: questions and doubts
Stent simulation with Abaqus: questions and doubts
(OP)
Hello everyone,
I am a researcher in the field of biomedical 3D printing and I need your help on a Abaqus software. I am a new user of this software, and I would like to ask questions to you who are more experienced than me.
I should achieve an opening simulation of a stent (medical device) within a vascular branch. I know all the physical-mechanical characteristics of the stent and the vessel in which the stent will be in contact.
I also followed several tutorials but I have some doubts. In particular I would ask the following information:
- Boundary Conditions: I have not figured out how I should set the boundary conditions of my system to enable analysis. I have to prevent the roto-translation for each elements (vase, baloon and stent) in all directions of the space?
- If I wanted to compress the stent of a specific amount, how could I do? For example: the initial geometry of the stent has a diameter of 30mm, with Abaqus I would like to apply constant pressure on the outer surface of the stent so as to compress it from 10mm up to do to reach its diameter to 20mm. How can I make something like that?
Thank you.
Luca
I am a researcher in the field of biomedical 3D printing and I need your help on a Abaqus software. I am a new user of this software, and I would like to ask questions to you who are more experienced than me.
I should achieve an opening simulation of a stent (medical device) within a vascular branch. I know all the physical-mechanical characteristics of the stent and the vessel in which the stent will be in contact.
I also followed several tutorials but I have some doubts. In particular I would ask the following information:
- Boundary Conditions: I have not figured out how I should set the boundary conditions of my system to enable analysis. I have to prevent the roto-translation for each elements (vase, baloon and stent) in all directions of the space?
- If I wanted to compress the stent of a specific amount, how could I do? For example: the initial geometry of the stent has a diameter of 30mm, with Abaqus I would like to apply constant pressure on the outer surface of the stent so as to compress it from 10mm up to do to reach its diameter to 20mm. How can I make something like that?
Thank you.
Luca





RE: Stent simulation with Abaqus: questions and doubts
Here is a thesis i found online after searching for about 2 seconds:
http://www.stent-ibitech.ugent.be/downloads/PhD_Ma...
Simulia also used to run training course on FEA of stents. If you contact them you might be able to get a copy of the notes. Finally, one of the performance benchmark analyses involves deployment of a superelastic stent. If you contact Simulia they will provide the input file for this analysis. You can find more details here:
https://www.3ds.com/support/certified-hardware/sim...
RE: Stent simulation with Abaqus: questions and doubts
3500elements have missing property definitions. The elements have been identified in element set ErrElemMissingSection
I noticed that there are many similar mistakes written on this form but nobody has a solution been indicated.
Can you help me to understand?
Thanks
Luca
RE: Stent simulation with Abaqus: questions and doubts
You mentioned that you are a new user of Abaqus. You should read the Abaqus Analysis Users manual and work through the problems in the Abaqus Example Problems Guide. And like I said earlier, look at what people have done in the literature and learn from their methods.
RE: Stent simulation with Abaqus: questions and doubts
I have solved the above problems and I'm able to successfully carry out the simulation. I'm studying a lot of literature to try to understand the physical and mechanical problems that exist behind the simulations and I'm learning a lot. However in publications rarely explains the process used in Abaqus to get that solution.
I need some advice, if possible.
As you see my stent during expansion it reduces its size in the z direction, changing frighteningly its length. This must not happen. The stent expansion must take place without changing the length of the stent.
How can I approach to solving the problem?
I've only Expand Step in which I've set a radial uniform Pressure Load and where BC's are:
Thank you
Luca
RE: Stent simulation with Abaqus: questions and doubts
Also, reconsider the mesh on your stent. It's not great.
RE: Stent simulation with Abaqus: questions and doubts
Are you suggesting me to reduce the size of the mesh to make it more compliant expansion of the stent? During meshing I entered values for reduce calculation times ... but I'd have to see them again ...
How can I measure diameter of final expansion compare it with the initial diameter? There is a function for this in Abaqus?
RE: Stent simulation with Abaqus: questions and doubts
If you want to measure the inner diameter you can probably just use the diameter of the expansion surface. If you want to measure the outer diameter you could just take measurements directly from the stent.
RE: Stent simulation with Abaqus: questions and doubts
RE: Stent simulation with Abaqus: questions and doubts
RE: Stent simulation with Abaqus: questions and doubts
If I understand you correctly you are suggesting me to design my stent in 2D with an external software (I use Rhinoceros and I have to continue using this software, I can not draw directly into Abaqus). Then I can export the 2D model of stent In Abaqus (.stp file?) and here I can mesh with hex and impose a thickness to my 2D model. At this point with the NMAP Abaqus function I can wrap my model to the cylinder. Did I get it right?
RE: Stent simulation with Abaqus: questions and doubts
See pages 63-64 of the following thesis:
https://dspace.lboro.ac.uk/dspace-jspui/bitstream/...
RE: Stent simulation with Abaqus: questions and doubts
What you're proposing is really useful to me. I'm trying to draw my cell stent in 2D and then apply mesh in Abaqus and wrap it around the cylinder with the NMAP command. I have another problem though.
My stent addition to opening should also go to "bump" against the vein that, in my case, is represented by a .stl file that comes directly from the patient's radiological images. My surface is this:
How can I import it in Abaqus and make it interact with my stent? I tried .stl import but does not work.
Thank you again.
RE: Stent simulation with Abaqus: questions and doubts
You will have to specify an interaction property between the stent and the vessel. Vessel will also have to be specified with some mean pressure, I'd imagine.
Simulia Learning Community has an excellent best practices document that is worth looking into.
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RE: Stent simulation with Abaqus: questions and doubts
RE: Stent simulation with Abaqus: questions and doubts
Hi Dave, I re-open this thread because I need to ask you a question.
If I'm not interested in using the FEA simulation to optimize the stent geometry but only to verify the fitting between the stent and artery it is necessary however that I use Hex Elements instead of tet elements?
Thanks
Luca
RE: Stent simulation with Abaqus: questions and doubts
Your stent geometry looks very simple to partition and hex mesh and your analyses would run quicker. If you are just interested in the deformed geometry of the stent I would still perform a mesh refinement study to ensure that your final geometry does not change by too much - the mesh you showed in your earlier posts looks extremely coarse.
RE: Stent simulation with Abaqus: questions and doubts
Assuming you want be good at computational FE analyses, and aside from your immediate requirements, hex meshing is an art you want to become good at for many reasons. It takes a lot of practice to "simplify" a geometry, subdivide it, and then mesh it just so that the ultimate stress field is orthogonal to the "flow" of the mesh - all in the name of quality work. This is a cost you pay up front in the life cycle of a model. If you'd rather use automeshing capabilities and start churning out data quickly, then the cost will very likely accumulate at the back end when you refine the mesh with other kinds of elements.
If a model is just for a quick demo of the possibilities, the results are not going to be consumed to make any design decisions, and the turn-around time is short, then the latter approach may very well be reasonable. However, as a practice, I take as much time up front as I can to generate a high "quality" mesh.
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