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Type: Posts; User: maas

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  1. Hi, Unfortunately, optimizing for the sum of...

    Hi,

    Unfortunately, optimizing for the sum of all the nodal reaction force is currently not possible in FEBio's optimization module. The contact approach with a rigid body is the only way I can...
  2. Hi Bradley, I'm not entirely sure what you...

    Hi Bradley,

    I'm not entirely sure what you mean by regularization, by I do know that a false dynamic response can often solve models that otherwise converge difficultly. In this case, you would...
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    Hi Nataliya, It's difficult to say how to...

    Hi Nataliya,

    It's difficult to say how to improve an optimization since there are many factors involved. Some things to consider are, is the constitutive model chosen the best one for what you are...
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    Hi Nataliya, 1) You can have FEBio output the...

    Hi Nataliya,

    1) You can have FEBio output the rigid body forces, either in the log file or the plot file. To add them to the plot file, add the "rigid force" plot variable to the plotfile section...
  5. Hi Jon, When using an uncoupled solid mixture,...

    Hi Jon,

    When using an uncoupled solid mixture, the best practice is to put the "k" parameter as a member of the toplevel "uncoupled solid mixture". However, FEBio allows placing the "k" parameter...
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    Hi, In FEBioStudio (PreView's successor) we...

    Hi,

    In FEBioStudio (PreView's successor) we have some ways to refine a volume mesh locally, but not a surface mesh. Since STL is only a surface mesh you need to generate a volume mesh first. Or...
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    Hi, I'm glad to hear you were able to make the...

    Hi,

    I'm glad to hear you were able to make the model run faster. I just wanted to add a comment on the max_retries parameter.

    In general there is very little gained from increasing this...
  8. Hi, Please check out the user manual section...

    Hi,

    Please check out the user manual section 4.1.1.1 on specifying fiber orientation. Based on your description, I think the "cylindrical" option is your best choice.

    Cheers,

    Steve
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    Hi, Tet4 elements have a tendency to lock,...

    Hi,

    Tet4 elements have a tendency to lock, which means they often under-predict the displacement. If you switch to higher order elements, you are most likely experiencing larger deformations,...
  10. Hi, I just tried it with FEBioStudio and it...

    Hi,

    I just tried it with FEBioStudio and it seems to work. If you have not switched to FEBioStudio, I highly suggest it since it is the new development environment for FEBio. We are no longer...
  11. Hi, There was indeed a bug in rendering hex27...

    Hi,

    There was indeed a bug in rendering hex27 elements in both FEBioStudio and PostView. If you reach out to me (steve dot maas at Utah dot edu), I can send you a new version to try. Thanks for...
  12. Thread: Post-View Springs

    by maas
    Replies
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    Hi Lexie, Yes, you would have to connect...

    Hi Lexie,



    Yes, you would have to connect the ACL to both the tibia and femur. You can do this by using rigid interfaces (menu Physics > Add Contact ..., and then select "rigid") and connecting...
  13. Hi, When you set the "surface_hint" flag to 1,...

    Hi,

    When you set the "surface_hint" flag to 1, FEBio assumes that the surface is a sphere centered at the origin. In your model, the sphere is not centered at the origin and FEBio is not...
  14. Thread: Post-View Springs

    by maas
    Replies
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    Hi Lexie, After you import the ligaments into...

    Hi Lexie,

    After you import the ligaments into PreView (or FEBioStudio), you can move, rotate, and scale the meshes into the correct position so it should be possible to align them correctly with...
  15. Hi Bradley, I took a look at your models and,...

    Hi Bradley,

    I took a look at your models and, after conferring with a colleague, suspect that you are seeing the expected behavior of this damage model under load control. Under force driven...
  16. Thread: Post-View Springs

    by maas
    Replies
    5
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    131

    Hi Lexie, Currently, FEBio doesn't store any...

    Hi Lexie,

    Currently, FEBio doesn't store any of the spring data (like stretch, and force) in the plot file. This is something we can definitely add and I don't think it would take very long....
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    Hi Alireza, Unfortunately, I don't think you...

    Hi Alireza,

    Unfortunately, I don't think you can edit the load curves of nonlinear springs in PreView. We will have support for this in FEBio Studio, which replaces PreView. In fact, if you reach...
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    Hi Laura, Sorry for the late reply. Have you...

    Hi Laura,

    Sorry for the late reply. Have you been able to make progress on this? I ran these models and I confirm the problems you are seeing. As far as what's causing them, my best guess at this...
  19. Thread: Load Choice

    by maas
    Replies
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    2,270

    The force that is exported is the net force on...

    The force that is exported is the net force on the center of mass of the rigid body. You can also export the net torque. See section 3.17.1.3 of the online user's manual.

    Cheers,

    Steve
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    Hi Jeremy, There is no limit on number of...

    Hi Jeremy,

    There is no limit on number of elements or nodes that you can use in FEBio. The only limit is the available memory on the computer. It could be a memory allocation failure. If you have...
  21. Hi Alexander, I'm not sure what could have...

    Hi Alexander,

    I'm not sure what could have caused this issue. If the mesh was modified in any way after the contact was already defined, then that could be a very likely culprit. If that did not...
  22. Hi, If you can send us the two models (the...

    Hi,

    If you can send us the two models (the displacement one and the force one), I'd be happy to take a closer look and see if I can spot any issues.

    Thanks,

    Steve
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    Hi Nataliya, You can find the release notes...

    Hi Nataliya,

    You can find the release notes online (although it looks it only goes to 2.9.0). You should also have the release notes as part of the FEBio installation. I doubt you would have to...
  24. Thread: Load Choice

    by maas
    Replies
    11
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    2,270

    Assuming that the nodal force is applied in the...

    Assuming that the nodal force is applied in the same direction as the average surface normal and the surface area isn't too big, then, yes, I think those two cases should produce similar loads in the...
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    Hi, A loadcurve scales the value of any...

    Hi,

    A loadcurve scales the value of any parameter to which it is assigned. So the actual value used in FEBio is the value entered for the parameter by the user, multiplied by the load curve value...
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