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Recent content by cavva78

  1. cavva78

    restart with modal frequency response analysis

    Sorry here are the correct linkshttp://files.engineering.com/getfile.aspx?folder=bfa4cb95-1580-498c-a44c-ebb93a4a4e05&file=modalfreqrestartnoresvec.zip http://files.engineering.com/getfile.aspx?folder=afd311a1-46d5-45e8-bf8b-bb8a688b0654&file=modal.zip...
  2. cavva78

    restart with modal frequency response analysis

    Dear Joe, I did some other tries but I'm not sure of what happened, restart still seems to be useless to me.. I'm attaching the following files: -.dat (without nodes and elements), .f04, .f06, .log of first modal analysis with database saving for restart (modal.zip) -.dat (without nodes and...
  3. cavva78

    restart with modal frequency response analysis

    Dear Joe, thanks for the reply. I also tried running a frequency response analysis with restart after a modal analysis disabling the RESVEC, but nothing changed in the running time... Always stting up everything from inside FEMAP 11.1.0. Marco
  4. cavva78

    restart with modal frequency response analysis

    Hello Joe, thanks for the reply. I'm not using the example problems but a model with about 100000 nodes and 800 modes in the first 2000 Hz, that's why I would like to use restart to avoid repeating the modal analysis every time I perform a random / frequency response run, it's very time...
  5. cavva78

    restart with modal frequency response analysis

    Hello, I'm using FEMAP 11.1 with NX Nastran for frequency response and random response analyses. Following tutorials I'm using the restart capability performing first a modal analysis then the frequency response (modal frequency method) using the saved database from the modal analysis. The...
  6. cavva78

    random response analysis with NX Nastran

    Hello, I'm performing a random response analysis with FEMAP 11.1 and NX Nastran on a model with a very high number of modes (about 850 from 0 to 2000 Hz). The PSD spectrum is in 20-2000 Hz range. The modal frequency method gives me a result with a modal critical damping of .03, although I had to...
  7. cavva78

    shock response spectrum analysis in NX.Nastran

    Dear Blas, thanks for the answer. I already read your tutorial, and I just have to perform a shock response spectrum analysis on an electronics box. I have my SRS input curve (acc vs frequency) from customer, to be applied to a base node connected to the box constraint points. My question is...
  8. cavva78

    shock response spectrum analysis in NX.Nastran

    thread825-258197 Hello, I'm performing a SRS analysis with FEMAP 11.1 and NXN 9.0. I'm following the FEMAP tutorial no.19 doing a modal analysis applying a SRS (acceleration vs. frequency)on a node with a large mass and a SUPORT entry in the excited DOF. My question is: is it mandatory to use a...
  9. cavva78

    Shock response spectrum analysis

    Dear NX.Nastran/FEMAP users, I have to perform a SRS analysis, applying a SRS load as follows to an assembly model: 500 Hz -> 500 g 3000 Hz -> 2000 g 10000 Hz -> 2000 g I have never done that: how do I apply this load to my model? Is there any tutorial or example available? Thanks Marco
  10. cavva78

    Shock response spectrum analysis

    Dear Nastran/FEMAP users, I have to perform a SRS analysis, applying a SRS load as follows to an assembly model: 500 Hz -> 500 g 3000 Hz -> 2000 g 10000 Hz -> 2000 g I have never done that: how do I apply this load to my model? Is there any tutorial or example available? Thanks Marco
  11. cavva78

    dimensioning of venting membrane

    Hello everyone. I'm working on this problem: I have to verify the good choice of a filtering/venting PTFE membrane with a porosity 0.2 micrometers. It's applied on a closed box that undergoes a thermal vacuum test inside a vacuum chamber, with a pressure change rate of 200 mbar/min, and it is...
  12. cavva78

    random vibration environment analysis

    Hello, I don't use NX but Nastran with Femap as pre-post, with the licence for dynamic analysis. I am able to perform freq response and to apply PSD, but I would like to know how to consider the results, since I can have PSD of component stresses, and not Von Mises. Is there any standard procedure?
  13. cavva78

    Leak rate conversion with different gases

    Hello, I have a requirement for a max leak rate with He in a pressure vessel (1e-4 mbar*l/s). I want to test it with pressure decay method, but using Nitrogen instead of He. What is the correct calculation of leak rate using Nitrogen, and the translation in max pressure decay (mbar/s)? The...
  14. cavva78

    random vibration environment analysis

    Hello everyone, could anyone plase tell me what is the correct procedure to perform a structural analysis by FEA on an item subjucted to random vibration? I work in aerospace field and use NX.Nastran with Femap. I know the input PSD for this item and I would like to verify its strength. It...

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