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Recent content by ThomasH

  1. ThomasH

    How can I get rid of free edges

    The first mode was an indicator the something was loose in the model. Good that it worked.
  2. ThomasH

    How can I get rid of free edges

    This may be a slightly rude thing to ask, but, have you checked the model for coincident nodes ? :)
  3. ThomasH

    Patran/Nastran Buckling Analysis – SYSTEM FATAL MESSAGE 7340 (LNNHERR)

    I think have encountered something similar. The problem might be that the static subcase buckles the structure. I that case you may be able to use part of the buckling load to "balance" the system.
  4. ThomasH

    Is it possible to build classic precast pre-tensioned data centers in seismic zones ?

    If you by "classic" mean a structure that is not designed for seismic loads, I think some modifications will be required. I was involved with projects several years ago when a client wanted to use a module based steel building concept in seismic zon. The original design did not consider seismic...
  5. ThomasH

    1/2 loading for 1/2 model in ansys?

    If this is for learning i would start with the full model and the full load. The I would continue with half the model and half the load. But this is not a general rule. To give you a very simple example, that you can try first. Perhaps, just to imagine it will be enough :). Imagine a simply...
  6. ThomasH

    1/2 loading for 1/2 model in ansys?

    If everything is symmetrical just apply the full load on the half vessel that you have modelled. But if you use symmetri you wall also automatically ignore certain effects that may be relevant. Like certanin buckling modes, if buckling is relevant.
  7. ThomasH

    Solid elements rotations in FEA

    I don't know what exactly you are trying to do. But this may help you a bit on the way. If you start with a rectangle with two parallel line pairs and four 90-degree angles, that is the undeformed element. If you now change the angles so that two will be larger than 90 degrees and two will be...
  8. ThomasH

    Thermal load with thermal gradient in structural analysis

    Impossible to answer without more information. But getting large loads or stresses due to thermal loads is not surprising in itself. The structure wants to deform in some manner due to the geometry and the thermal load. And the boundary conditions prevent that deformation. One option is to...
  9. ThomasH

    One Drive - Am I the Last Person Using Dropbox for Business

    Perhaps not entirely relevant since I am in Europe but we use several services. What we don't use, as far as I know, is Dropbox. But I have a software vendor that distributes software with Dropbox. It works, but I just download a installation file. I have two computers. One good thing with...
  10. ThomasH

    What is the best way to reduce the weight of a steel beam without compromising its strength?

    I agree with a lot of what has already been said. But I can't help wondering, what is the purpose of the question? The reason I ask is because you are registred as a Student, and I think the question could be very good from a teaching perspective. Instead of making a lot of repetitive beam...
  11. ThomasH

    Torsional vibrations

    Greg Thanks a lot for your help. I have enclosed a pdf with my calculations and no the results are more reasonable. It's not perfect yet but we are not "stuck" anymore. And the students also say thanks.
  12. ThomasH

    Torsional vibrations

    Greg, You mentioned 80 Hz in a previous post, was that based on a hand calculation or FEM? If it was a by hand I am very interested in the details, if it was FEM, I have the same result. I am a but stuck with this right now :(.
  13. ThomasH

    Artificial Intelligence in Structural Engineering

    I occasionally use ChatGPT, mostly for fun but sometimes work related. I basically consider it an advanced web browser. I think it can be useful for translations. It can help me regarding formulations it I want things more or less formal. It is not perfect but significantly better than Google...
  14. ThomasH

    Torsional vibrations

    That was very interesting. The reason for the question is that with FEM we get the same result as the formula for bending. For torsion we get 80 Hz with FEM. The difference between Kv1 and Kv2 is supposed to be thin vs thick walled tube. But I find the difference between them strange since I...
  15. ThomasH

    Torsional vibrations

    Sorry, I should have been clearer. It is only an example and I need the formula for the first torsional mode of a steel tube. Preferably with a reference, then we can hopefully find the reference. I thought I had attached two files. I will try again. Thanks Edit: I could not attach a Mathcad...
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