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  1. isponmo

    External superelements / model reduction questions

    Dear dmapguru, Once again, thank you for your reply. It is clear now! It is shame there is no easier way than dealing with DMAP alters. Kind regards
  2. isponmo

    External superelements / model reduction questions

    Dear dmapguru, Thank you very much for your very detailed answer, it is really useful!! I will take the opportunity to ask a related question: for condensed models in OP4 format, which are included in the subsequent runs with the ASSIGN command (so, contrary to the DMIG case, here the K, M...
  3. isponmo

    External superelements / model reduction questions

    Dear eng-tip community, I have a couple of questions regarding external superelements originated from condensating a full FE model via EXTSEOUT command. The condensed models I typically work with (or generate) are obtained using dynamic reduction (CMS). Therefore, using SOL103 for the...
  4. isponmo

    Implicit vs Explicit Solver for Wave propagation problems

    Thank you for your answer! It is clearer now.
  5. isponmo

    Implicit vs Explicit Solver for Wave propagation problems

    Dear Eng-tip users, I have a question regarding the analysis of shock wave propagation problems in structures using FEM. Recently I was told that it is not possible to model shock wave propagation using implicit FEM schemes. The argument was that implicit schemes do not include this phenomena...
  6. isponmo

    Design limit loads and Structural design process

    Dear GrandpaDave, Thank you very much for your answer. It sounds like you had a very nice professional career. Hopefully one day I will be able to say the same! For the moment, though, I am just a beginner. :) So static load factors... I suspected that answer, but it is something I cannot...
  7. isponmo

    Design limit loads and Structural design process

    Hello! I have a question about how strength should be assessed in satellites structures and their payloads. I have seen different ways of doing the task, and it is not clear to me what is right and what is wrong. Some people calculate stresses directly from dynamic loads caused by random and...
  8. isponmo

    Contact in frequency response analysis

    Hi, Thank you guys for all your answers! Have a nice week :) Cheers!
  9. isponmo

    Contact in frequency response analysis

    Dear Blas, I am not able to totally understand: The sliding condition with friction is kept during the frequency response analysis? Or are the contacts frozen as I suspect? And can separation happen once the parts have been in contact, for the same frequency in a frequency response analysis...
  10. isponmo

    Contact in frequency response analysis

    Dear Blas, Thank you very much again. How is the contact condition defined mode by mode? How does the software define which interfaces are to stay open and which ones are to stay close? And still, even if for each mode the contact conditions are defined independently, I don't see how does...
  11. isponmo

    Contact in frequency response analysis

    Dear Blas, Thank you for your reply. If I understood it correctly, what the software does is defining open and close contacts during the static analysis, and applying the resulting contact states to the subsequent analyses. Consequently, the contacts that are closed, remain like that during...
  12. isponmo

    Contact in frequency response analysis

    Dear GregLocock, Thank you very much for your fast answer! :) Do you know a good source where I could find further information about synthesizing ASD back to time applied to FEM? Is this process a common practice? Why wouldn't you trust the results? I imagine that if we convert a ASD load...
  13. isponmo

    Contact in frequency response analysis

    Dear GregLocock and spongebob007, Thank you for your answers. I agree tata using non-linear transient analysis is the most accurate approach, but sometimes it seems impractical. For example, for a random vibration analysis it is not possible (as far as I know) to convert the load, described in...
  14. isponmo

    Contact in frequency response analysis

    Dear All, I have a FE model in which two of the parts touch each other but do not remain in contact all the time. The aim of the model is to estimate the stresses caused by an event defined in the frequency domain. As a first step, I did a normal modes analysis ignoring the contact between...
  15. isponmo

    Weld Analysis Standards

    Thank you very much for your answers! Very useful information!
  16. isponmo

    Weld Analysis Standards

    Dear Eng-Tip community, I am looking for references for the design and strength analysis of welded connections. In particular, I am wondering if there is an equivalent to the existent guidelines for systematic analysis of threaded joint (such as the German VDI2230). I have checked some books...
  17. isponmo

    Meshing Approaches

    Dear Rob and Rick, Thank you very much for your comments. I understand them and find them very valuable. :) Kind regards, I.
  18. isponmo

    Meshing Approaches

    Dear Rick, Thank you very much for your answer. It is clearer now :) Just another question: considering the computational power we have nowadays, is it really worth spending time creating two models, one for stiffness with shells and another with solids for stress? Or is it better to go...
  19. isponmo

    Meshing Approaches

    Dear All, This is a rather basic question, but it still confuses me a lot: what is the best meshing approach? Meshing everything in detail, with fillets, etc.? simplifying the geometry and removing small features? Using solid elements for everything? Using shells for thin parts? I guess the...
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