How do I fix the time step in nonlinear transient analysis?

gslee
gslee New Altair Community Member
edited October 2020 in Community Q&A

Hi,

 

My loadstep, TSTEP and NLPARM are as follows

image.png.3e55a30feff8b485292c4af8a4511069.pngimage.png.83e3dc3ffa6bee0c4d9bf3101ffccf17.pngimage.png.28c2c5a0e6832950c397bdb1f1b4d6db.png

 

In the result, the number of the time data is 432. (Its time step is not 0.0001)

 

I learned that when NLPARM and TSTEP are used together, DT on NLPARM overrides DT on TSTEP.

 

This result is caused by incremental load based approach in OptiStruct?

 

Thanks

 

 

 

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Answers

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited July 2019

    Please refer attached document for nonlinear transient analysis setup.

    Unable to find an attachment - read this blog

  • gslee
    gslee New Altair Community Member
    edited July 2019

    I think there is no way to fix the time step in pdf file.

     

    image.png.ff6c7104b237044bc05ead85ec65c407.png

    In nonlinear transient analysis, I can control only initial time step size?

     

    Thanks.

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited July 2019

    Time stepping scheme selected using TMTD parameter on TSTEP card.

  • gslee
    gslee New Altair Community Member
    edited July 2019

    Thanks

  • Jaseguras
    Jaseguras Altair Community Member
    edited January 2020

    Hi Rahul,

     

    Why do you defined DT and TTERM equal (0.1) in the pdf example you shared? It's not supposed that TTERM should be set to the whole subcase time? As stated in the optistruct help.

     

    TTERM on NLPARM is to be input based on subcase time (not total time). For instance, in a multiple subcase setup, if subcase 3 starts at 2.0 and you want it to end at 3.0, then TTERM for subcase 3 should be set to 1.0 (since it is based on subcase time).

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