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  1. Hi Adam, One thing we should keep in mind is...

    Hi Adam,

    One thing we should keep in mind is that these benchmark problems are designed specifically to be challenging for contact algorithms. The concentric spheres benchmark has very coarse...
  2. Hi Adam, The particular test problem you chose...

    Hi Adam,

    The particular test problem you chose (compression of concentric spheres) is an interesting one because it exhibits a material instability, where the onset of the instability is governed...
  3. Hi Prashant, I was able to spend a few minutes...

    Hi Prashant,

    I was able to spend a few minutes with your models and noticed quite a few things which are preventing convergence.

    First, for wedge test 1.2:

    In the sliding-elastic contact...
  4. Hi, When you fix the nodes you actually...

    Hi,

    When you fix the nodes you actually completely remove those degrees of freedom from the problem, which is why there are no reaction forces (it looks like you are getting zero reaction forces,...
  5. Hi Lewis, I ran your model and it appears to...

    Hi Lewis,

    I ran your model and it appears to work perfectly. Could you clarify what problems you are having?

    Your deformation is very small, because you are only requesting a step displacement...
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    Hi Muhammed, I would recommend using...

    Hi Muhammed,

    I would recommend using "sliding-biphasic". "sliding-biphasic" is the more recent implementation of biphasic contact and generally gives better results.

    Brandon
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    Hi David, I believe the purpose of these test...

    Hi David,

    I believe the purpose of these test suite problems is simply to demonstrate sliding-elastic contact working with shell elements. Shell elements are not needed for the contact.

    Brandon
  8. Thread: Contact

    by brandonz
    Replies
    2
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    339

    Hi Roxana, In any type of sliding contact, an...

    Hi Roxana,

    In any type of sliding contact, an initial overlap is only required for force-control problems. This is because at the first iteration of the first time step a contact force is needed...
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    Hi bhendo, I am attaching a model using...

    Hi bhendo,

    I am attaching a model using sliding-elastic contact which does what I described. It sounds like you had the right idea.

    You should note that contact algorithms in FEBio require the...
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    508

    Hi bhendo, You have a few minor mistakes. You...

    Hi bhendo,

    You have a few minor mistakes. You created a cube of a neo-Hookean material, and you created a rigid body which is properly constrained. However, right now your rigid body is not doing...
  11. Hi Stephen, I am running your model with...

    Hi Stephen,

    I am running your model with FEBio2.9.1 on a Mac and the analysis is converging nicely - I cannot reproduce your error.

    Is there any chance you did not store the geometry and mesh...
  12. Hi Stephen, You can email the geometry and...

    Hi Stephen,

    You can email the geometry and mesh files to bkz2101 at columbia dot edu.

    Thanks,

    Brandon
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    Hi Vaishakh, If you go to...

    Hi Vaishakh,

    If you go to https://febio.org/febio/febio-downloads/ you will see blue text that says "Previous versions" beside the version number of the current release. If you click this text it...
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    Hi Roxana, There were several errors with the...

    Hi Roxana,

    There were several errors with the files you sent me.

    In the model file:

    You had max_refs = 1. This meant you were only allowing your model to try 1 iteration per time step, so...
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    Hi arion, There is potentially another option....

    Hi arion,

    There is potentially another option. We are also working on a contact interface which is intended to represent tissues connected by fascia or implicitly defined fibers. The interfacial...
  16. Hi Ann, I looked at your PreView model. In the...

    Hi Ann,

    I looked at your PreView model. In the contact named "Sliding-elasticContact1", your master is Surface8 and your slaves are Surface17 and Surface19. However, if you select Surface17, you...
  17. Hi Joe, I found out how to reproduce your...

    Hi Joe,

    I found out how to reproduce your error. My IDE is Xcode and in the FEBioOpt project settings for my compilers there is an option for other flags. For the Intel compiler, look under...
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    Hi Jeonghun, Create two cylinders in PreView,...

    Hi Jeonghun,

    Create two cylinders in PreView, where the outer radius of the inner cylinder matches the inner radius of the outer cylinder. You then have two options, depending whether the objects...
  19. Hi Joe, I just rechecked these files, using...

    Hi Joe,

    I just rechecked these files, using version 2.8.5 on a Mac and they ran as expected and did not reproduce your error. What operating system are you using?

    Brandon
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    Hi Shady, I did not get your model to work,...

    Hi Shady,

    I did not get your model to work, but I think I have identified a few reasons why it was not running. I'll explain my thought process in case it is helpful for your future debugging...
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    Hi Shady, Your link does not appear to work...

    Hi Shady,

    Your link does not appear to work for me.

    Brandon
  22. Hi Michael, Open your model in PreView, select...

    Hi Michael,

    Open your model in PreView, select the object, and right-click "Show Normals". The normal vectors on your cartilage piece are all pointing outward. The normal vector on your...
  23. Hi Michael, In a solid mixture, you can...

    Hi Michael,

    In a solid mixture, you can reference the components through an index. In your case, you would need to do

    fem.material('Cartilage.solid.solid[0]').E
    for Young's modulus of the...
  24. Thread: jagged plot

    by brandonz
    Replies
    3
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    498

    You can email me at bkz2101 (at) columbia (dot)...

    You can email me at bkz2101 (at) columbia (dot) edu. It would be helpful if you could send an example of a "smooth" plot and one of a "jagged" plot.

    Brandon
  25. Thread: jagged plot

    by brandonz
    Replies
    3
    Views
    498

    Hi Jeonghun, Could you attach plots or .feb...

    Hi Jeonghun,

    Could you attach plots or .feb files to help us understand what you mean?

    Brandon
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