Buckling of 1D PBEAML Elements

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

Hello,

 

is it possible to analyze buckling and the deformation of 1D PBEAML elements? If, which steps are necessary?

 

Thank you!

Dave

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Answers

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited September 2015

    Hi,

     

    From the documentation of Optistruct user guide it looks like that it should work. Attached is the screenshot of user guide & highligted element will be ignored for buckling analysis.

    Please give try using Pbeaml element.Step by step tutorial is available in Optistruct tutorial for buckling analysis using solid elements.

     

    Regards

    Rahul R

    <?xml version="1.0" encoding="UTF-8"?>post-36845-0-48194600-1442294590_thumb.j

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited September 2015

    Hi Rahul,

     

    thanks, but the big question is - how? I used Pbeaml's, but there is no buckling information available if I do a EIGLR analysis! Do you have any further information or maybe experience on that?

     

    Best regards,

    Dave

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited September 2015

    hi dave,

                what  loadstep did you define for this?. select type as linear buckling type.  In STATSUB option select the first loadstep, if you have any other load atep defined, and in METHOD(STRUCT) select the EIGRL card you have created.

     

    hope this works.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited September 2015

    Hi sbx626,

     

    linear buckling is defined. The buckling loadstep is working and delivers results for 2D elements. But there are no solutions for all used 1D elements image/emoticons/default_sad.png' alt=':(' srcset='/emoticons/sad@2x.png 2x' width='20' height='20'>

     

    Thanks for your support,

    Dave

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited September 2015

    hi dave,

     

    please make sure that you selected the correct loadstep/subcase from  the result browser in HV. It is possible to view the result for 1-d elements in linear buckling analysis.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited September 2015

    Hello sbx626,

     

    thanks for your support! I think the setup is okay. Now I get displacement, stress and buckling values. The CBAR/STRESS under result type of the contour plot is showing negative values. What does that mean?

     

    Here are a few screenshots, with obtained results:

    <?xml version="1.0" encoding="UTF-8"?>post-36975-0-81833700-1442732013_thumb.p

    <?xml version="1.0" encoding="UTF-8"?>post-36975-0-89265200-1442732014_thumb.p

    <?xml version="1.0" encoding="UTF-8"?>post-36975-0-08834600-1442732016_thumb.p

    <?xml version="1.0" encoding="UTF-8"?>post-36975-0-96315600-1442732017_thumb.p

     

    Thank you!

    Dave

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited September 2015

    Dave,

     

    A buckling mode with a negative buckling load factors means the load direction must be reversed for buckling to happen.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited September 2015

    The load direction should exactly cause buckling. Most critical / relevant load cases were selected, like this |-. Sorry but this can't be the problem in this case.

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