Stent Expansion Contact Interface Questions

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  • car207
    Junior Member
    • Jun 2020
    • 22

    Stent Expansion Contact Interface Questions

    Hello,

    I am trying to expand as tent within the pulmonary arterial root. For now, the stent is simply modeled as a cylinder which gets expanded by placing the stent on the origin, prescribing X displacement: </math> 0.1*X</math>, and Y displacement </math> 0.1*X</math>. I'm running into a few issues with this. First, stent always pops open on the very first time step, no matter how small or what the load curve dictates. This is not the case when I just prescribe a constant as opposed to using <math> tags.

    Secondly, I cannot find contact interfaces that work for this expansion. I've tried starting the two surfaces already together (though not ideal for this simulation), merging geometry, and a variety of the different sliding and contact interfaces. I simply need the stent to not be able to penetrate the artery but cannot figure out how to achieve this. Part of the issue might be my instantaneous stent opening, but there might be other issues at play. I would really appreciate some help. Unfortunately, the files are too large to attach to this thread. Let me know if you need more information.

    Thank you in advance!
  • ateshian
    Developer
    • Dec 2007
    • 1824

    #2
    Hi,

    If you could create a smaller model that re-creates your problem and share it, that would be helpful. Otherwise it is hard to figure out if this issue is related to the mesh, material properties, contact interface, etc., that your model uses.

    Best,

    Gerard

    Comment

    • car207
      Junior Member
      • Jun 2020
      • 22

      #3
      Hi Gerard,

      Unfortunately, I cannot get the file to be small enough without compromising the geometry, mesh, contact interfaces, etc. Even when I eliminate everything except for the geometry of the stent and pulmonary artery, it is still too big to attach to this thread. When I create a simple tube with a much less fine mesh, the files still are too big. Is there any chance I could email you my file?

      Thanks,
      Carly

      Comment

      • ateshian
        Developer
        • Dec 2007
        • 1824

        #4
        Hi Carly,

        Yes, you can email me the file (or a link to it): ateshian@columbia.edu.

        Best,

        Gerard

        Comment

        • ateshian
          Developer
          • Dec 2007
          • 1824

          #5
          Hi Carly,

          I looked at your model and here are the things you need to modify:

          1) The pulmonary artery mesh is not hollow, which means that there is no inner wall against which the stent can push. You need to re-segment the geometry to include the lumen and only mesh the arterial wall. (The same should probably be done with the aorta, but that's not relevant to your objective of having the stent expand within the pulmonary artery.). Then you can create a contact interface between the cylindrical surface of the stent and the lumen (endothelial) surface.

          2) Your model has three parts (Stent, AR and PA), but the only one which is constrained with boundary conditions is the stent. While you do have a contact interface between the aorta and pulmonary artery, that's not sufficient to prevent these parts from separating. You should properly constraint your model to prevent any part form 'flying away'.

          Best,

          Gerard

          Comment

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