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    • Rahul Ponginan

      Please click here for a short but important announcement   03/26/17

      Dear Users Our Commercial and Academic users around the world can use these same forums here as before i.e. the Altair Support Forum , Commercial users from India with solver queries can go to the Solver Forum for India Commercial Users , Academic Users from India and AOC India Participants are requested to go to the Forum for India Academic Users and AOC India Participants , We will be tending to all queries in all the forums promptly as before, thank you for your understanding. 

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Found 14 results

  1. 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
  2. Hypergraph

    Hello, I am doing FRF. I want to plot Stress vs frequency plot in hypergraph. But result for nodes above 10000 is not showing. Please help me. Regards Rajendra
  3. How do I plot an amplitude vs. frequency graph with the results generated in Inspire Motion from a sine-sweep actuator? I can export the displacement results vs time but I'm not sure if performing an FFT on it will give me what I want?
  4. What card or factor should I input to get the FRF plot of the modes and frequency I am getting from modal analysis in optistruct.
  5. Hi Guys.... Is there any method or thumb rule to calculate the calculation time of a direct frf solution. I have a small system with 64GB RAM but large number of nodes to calculate, can anyone suggest any thumb rule over number of nodes to calculate, number of frequencies to output and system specifications. Also, is there any thumb rule that the performance of an frf is maximum with 4 cores?? I read it somewhere.... Thanks in advance
  6. FRF in rectangular coordinates

    Hello, When I do the FRF analysis and visualize the responses in Hypergraph they appear as magnitude and phase, how can I get these answers in rectangular coordinates (real and imaginary) directly?
  7. FRF as complex number

    Hi, I'm doing FRF direct with OptiStruct. When I extract the answers in HyperGraph, the magnitude and phase appear separately, how can I get this answer as a complex number?
  8. Frequency domain LS Dyna

    Hello, I'm using hyperemsh to carry out a dynamic analysis with LS Dyna implicit solver. I'm using Hypermesh 14. I'm trying to do a frequency analysis but I can't find the keyword FREQUENCY_DOMAIN in the solver browser. The version in the LS Dyna user profile is the 8 so there should be the option for frequency domain analysis. Any ideas? Thanks, Stefano
  9. Hi sir, I am getting an error while solving FRF analysis, i.e. *** ERROR # 2094 *** EXCITEID on RLOAD2 # 9 data references follower force or nonexistent DAREA/static loading with ID # 4. ************************************************************************ There were 2 error messages during input processing. The first message is repeated below: *** ERROR # 2094 *** EXCITEID on RLOAD2 # 9 data references follower force or nonexistent DAREA/static loading with ID # 4. ************************************************************************ ==== End of solver screen output ==== ==== Job completed ==== Please help me, as I am running out of time. Regards Rajendra Prasad Borgwarner
  10. Modal analysis of rotor

    Hi , I am working on modal analysis of rotor system in optistruct. I have queries regarding constraints. Pls find the following image which shows rotor assembly with bearing. I need to allow rotation free of rotor and shaft at bearing locations. How to give constraints at bearing locations ? Using RBE2 or any other options are there in Optistruct? Thanks Arul
  11. Messages for the job: *** ERROR # 5408 *** Aborting analysis because no structural modes have been computed in the modal dynamic subcase 1. *** PROGRAM STOPPED: FATAL ERROR(s) ENCOUNTERED. I am not understanding why this error is comming. Please help me.
  12. In optimization for FRF, it's very useful to run modal analysis once before getting FRF results in multiple load conditions (e.g different Fx Fy Fz on same structure ). Hope you can let me know how to set this option.Thanks!
  13. Is it possible to define the contact ( surface to surface , single surface contact) between components in vibration analysis ( Modal , FRF) in optistruct?
  14. FRF analysis ERROR # 151

    Hi Prakash, I am running a Direct FRF analysis in Optistruct. I have asked out on only 2 frequencies. I am attaching my .out and .stat file here and error message also. Please resolve my issue. *** ERROR # 151 *** Error accessing the scratch files: error encountered in subroutine "xzslvn" Solver error no. = -410 index = 1 This may be caused by insufficient disk space or some other system resource related limitations. (e.g. The Operating System or NFS cannot handle file size > 2 GB.) This error was detected in subroutine inptvmc. **** ABORTING RUN DUE TO UNEXPECTED ERROR CONDITION **** **** Job completed **** Thanks Hemanshu