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denizbilgili

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  1. Thanks Prakash. Sorry, I thought the case was forgotten. I have checked the .fem and .mnf you shared. In MODEL, Elset is set to ALL but the docs say for CMS SE generation it is defaulted to NONE. But mnf OUTPUT captures no modes in the mnf file when it is set to NONE so I think we'll have to wait for the devs to share what they find. I'll be waiting for your response. Thank you for your time.
  2. Hello, I would like to remind that I am still looking for a way of generating superelements with Craig-Bampton Method in Optistruct for Adams (MNF file format). I would like to know if there is a way around. So far, I have tried a few ways combining PLOTEL, NORIGID and NONE in the MODEL card but still no luck. Thank you.
  3. Hello Prakash, I have set V1 = 0 and requested 10 modes. .out file now gives the total mass (3.14e-5) as you have also obtained in your results. Though, there are small differences in individual modal masses between your and my results, but I don't think that's an issue. Thank you very much for your help.
  4. Hello Prakash, I have tried as you said, the problem still exists. On the machine with 2017 build, there are no problems, everything works both with DISPLACEMENT and ACCELERATION. However in 2017.2, I am unable to select response node sets for DISPLACEMENT and ACCELERATION entries. I have tried two machines with 2017.2 build installed, the problem was seen on both machines. Thank you.
  5. Hello Prakash, Thank you for your response. I have a node set for response calculation and I am able to select this node set for the SID entry in DISPLACEMENT. However, I am unable to select this same node set for the SID entry in ACCELERATION. When I enable ACCELERATION and click on Option -> SID, the window that pops up showing available node sets for selection is empty. So it doesn't let me select that node set for ACCELERATION. I'm outputting using HGFREQ and I am able to solve the model and plot the results in HyperGraph if I use DISPLACEMENT. However, since it doesn't let me select the same response node set in ACCELERATION, I'm unable to run an analysis using ACCELERATION. Thank you. Update: I have just noticed that I can't select any node sets in DISPLACEMENT too. This is happening in version 2017.2. Yesterday I was able to select node sets in version 2017. I will check back with my 2017 build as well as on different machines with 2017.2 build and update my answer.
  6. Hello, I am using Optistruct to numerically calculate some FRFs. I have test data to validate my numerical results. Measured test data is an FRF data in the form of Inertance (acceleration/force). I see that there is a big gap in frequency components' amplitudes between the measured data and numerically calculated data, though calculated and measured natural frequencies align very well. I have followed the modal frequency response tutorial and nowhere in the tutorial is it shown that we're specifically selecting the type of FRF we're wanting (e.g. inertance or mobility or receptance). GLOBAL_OUTPUT_REQUEST is used with DISPLACEMENT enabled and that makes me think that, what I am calculating in Optistruct is Receptance and not Inertance. I tried to request ACCELERATION instead of DISPLACEMENT, but ACCELERATION doesn't let me select the output node set which I used for DISPLACEMENT. How can I make sure in Optistruct that the numerical data I'm getting is inertance and not mobility (velocity/force) or receptance (displacement/force)? Best regards
  7. Hey Prakash, if you check the .mass file I shared in my previous posts, you'll see that the numbers don't add up to 3.14e-5 tons, which is the total mass of my test structure. In fact, the numbers are way higher than the total mass of my system. Attached is the .fem file for my test structure and modal analysis. I would be grateful if you could share more information with me on this. Thank you for your time. effmass.fem
  8. I would like to remind you my last inquiry. As I said, I am able to print the results to the HG file, however I am unable to interpret the results. My model uses metric tons for mass unit, how can I interpret the results and see if they add up to 90% of total mass or not? Thank you
  9. Thanks Prakash. As I said, I am able to output the results now. However they don't add up to the total mass of the system so I would you to share with me more information on the units used in the .mass file. Thank you I have added a screenshot of hypergraph plots. X and Y axes are not labeled so I'm unable to interpret the plot.
  10. Hello Prakash, I added the OUTPUT card with HGEFFMASS selected, however I don't see any option asking me where to write it. I checked the docs on HGEFFMASS and it says: and says *.mass and *_mass.mvw files are used to store modal effective masses. I do get these files so I used HyperGraph to plot the .mass file Optistruct generated. There is indeed some data in it but they aren't labeled properly so I don't know which data represents which property. I would like more help on this. Also, the entries in out file are the same as I posted above. ADDITION: I have seen the doc pages for .mass and _mass.mwv files. Attached is my .mass file. I have understand that the rows are for each requested mode and columns are for subcases. However, I don't know the unit of these values. The total mass of my test system is 3.14e-5 tonnes, or 31.4 grams. The magnitudes in the .mass file are very large compared to my total mass if .mass file gives modal effective masses in my units. Could you tell me what unit .mass file uses? Thank you effmass.mass
  11. Hello Prakash, I have tried both in 2017 and 2017.2. They're generating the same results in the .out file. Results from a sample for effmass is attached. It seems to be working but my problem is I can't see any entries for modal effective mass in this output. Thank you effmass.txt
  12. I have a relatively large flexbody model and I want to make sure that I include the absolute minimum number of flexible modes which will still be sufficient to model the system's dynamics. I want to use modal effective mass approach and include a number of modes such that those modes' total modal effective mass corresponds to about 90% of the system's total mass.
  13. I would like to remind you my inquiry. I didn't want to start a separate topic since this one is on the exact same subject. Thank you for your time.
  14. Hello Prakash, Attached is an example file modelled in the same way as I always generate flexbody models. Since I cannot share an original model file, attached model consists of a very simple geometry. Kind regards altair_cms_adamsmnf.fem
  15. I would like to know this as well. I am using PARAM, EFFMAS to calculate modal effective mass and I am getting similar results, but I don't know how to calculate the effective mass of each mode with given data in the out file. I would be happy to know how I can obtain modal effective masses using Optistruct.
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