Direct frequency response analysis

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Hi,

 

I am running a direct frequency response analysis in Optistruct. I have only managed to obtain the displacement-freq. and the phase-freq. graphs in Hypergraph. How do I obtain the stress distribution on the model? Does it have anything to do with the Control Cards?

 

Thanks,

Ginobili

 

Tagged:

Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2015

    There are two ways to output or plot frequency Vs stress using the below case control command:

     

    STRESS = ALL

     

    You can import the .h3d file to HyperGraph and plot the results.

     

    You can also plot the same in HyperView itself, split the window into two in HV and bring HyperGraph in the second window and use build plots.

    <?xml version="1.0" encoding="UTF-8"?>post-7616-0-08323500-1423630007_thumb.jp

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2015

    Thanks very much, Prakash. It helped in finding the elemental stresses. How do I find the nodal stresses? GPSTRESS says it outputs stresses at grid points. Are grid points and nodes the same?

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2015

    Hi,

     

    If you want to plot only the nodal stress then request the below output in the deck as case control command and Import the .pch file to HyperGraph:

     

    GPSTRESS (PUNCH, VON) = ALL

     

    Please note that currently GPSTRESS output is available only for solid elements.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2015

    Hi,

     

    When I output the element stress results for Von Mises stresses, how do I find the resultant of the stresses? All I see here are options to view the XX, YY, ZZ, XY, YZ and ZX stresses. I appreciate your help.
    After navigating as follows in the help menu, Optistruct -> Reference Guide -> Input Data -> I/O Options Section, I find this written in the comments at the bottom of the page: 'The Von Mises and Principal stresses are not available for frequency response analyses.' Does this mean I can't obtain these stresses using Altair's tools? I don't want my effort to go down as a lost cause. image/emoticons/default_sad.png' alt=':(' srcset='/emoticons/sad@2x.png 2x' width='20' height='20'>
     

     

    Thanks,

    Ginobili

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2015

    Hi Ginobilli,

     

    Could you please let me know what is the use case for having a stress-freq curve?

Categories