Geometric non-linear Implicit Dynamics

RAMGANESH
RAMGANESH Altair Community Member
edited October 2020 in Community Q&A

Dear All,

 

Any tutorial for Geometric non-linear Implicit Dynamics analysis???

 

Thanks

RAM

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Answers

  • Subhu_21017
    Subhu_21017 Altair Community Member
    edited February 2017

     

    OS-1500: Nonlinear Implicit Analysis of Bending of a Plate

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Hi Ram,

    Please go through these case studies: http://www.altairatc.com/india/bangalore/technical-presentations.htm

  • RAMGANESH
    RAMGANESH Altair Community Member
    edited February 2017

    Dear George,

     

    I had tried to solve my problem using  Geometric non-linear Implicit Dynamics analysis .

     

    Total run time is for 21 seconds but it is solving for 15 seconds then shows the below error.

     

    Following error occurs after some iterations.

    MESSAGE ID :           79

     ** ERROR : RADIOSS IMPLICIT STOPPED DUE TO TIMESTEP LIMIT **

          ISTOP=-2

     

    Please provide your guidelines.

     

    Thanks

    RAM

     

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Hi Ram,

    When the time step is smaller than the input minimum one (please check /IMPL/DT/STOP), RADIOSS will stop the run with this message.

    The reason is generally due to the convergence issue (DT_min). There is no general workaround for convergence issue, as outlined below:

     

    1.Check the model, constraint conditions, materials, contact interface defines and so on.

    2.Switching other convergence criteria (see Itol in /IMPL/NONLIN).

    3.Try /IMPL/NONL/SMDISP to see if the issue came from geometric nonlinear

  • RAMGANESH
    RAMGANESH Altair Community Member
    edited February 2017

    Dear George,

     

    After reducing the minimum timestep DT in TSTEPNL ,

     

    i didn't get this error.

    Following error occurs after some iterations.

    MESSAGE ID :           79

     ** ERROR : RADIOSS IMPLICIT STOPPED DUE TO TIMESTEP LIMIT **

          ISTOP=-2

     

     

    But it shows this error

     

    ** ERROR : RADIOSS IMPLICIT STOPPED DUE TO SOLVER ERROR **

     

           ISTOP=-4

     

     

    Please provide your guidelines

     

    Thanks

    RAM

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Below are the suggested workarounds for error   ISTOP=-4:

     

    1.Check which solve method is used in /IMPL/SOLVER. Use another solve method.

    2.Another frequent case is when the model is relatively large and the available free disk is not large enough.  If the issue came from memory management, you could also force RADIOSS to use out-of-core resolution (/IMPL/SBCS/OUTCORE).

     

    Please try with these options.

  • RAMGANESH
    RAMGANESH Altair Community Member
    edited February 2017

    Dear George,

     

    How to change the solver method?

     

    Thanks

    RAM

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Hi Ram,

    I presume that you are working on OptiStruct Profile.

    Create a load collector with SOLVTYP as card image and Create/Edit it. You will get the options to change the solver type. Try with AUTO which automatically selects between BCS and PCG type.

    Finally, edit the load step and recall the  SOLVTYP you have created.

    <?xml version="1.0" encoding="UTF-8"?>Capture.PNG

    <?xml version="1.0" encoding="UTF-8"?>Capture2.PNG

  • RAMGANESH
    RAMGANESH Altair Community Member
    edited February 2017

    Dear George,

     

    Yes ,i am using Optistruct and created the load collector with SOLVTYP card as you mentioned.

     

    I am choose analysis type as Geometric Nonlinear Implicit dynamic analysis  in Solver Definition in load step

    In SUBCASE option ,the SOLVTYP is not available  and unable to recall it.

     

    please give your valuable suggestions

     

    Thanks

    RAM

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Hi Ram,

    Ill update you regarding this.

     

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Hi Ram,

    It is not possible to change the solver type for dynamic cases.

    Please share the .out file.

  • RAMGANESH
    RAMGANESH Altair Community Member
    edited February 2017

    Dear George,

     

    Shared files in your dropbox

     

    Thanks

    RAM

  • RAMGANESH
    RAMGANESH Altair Community Member
    edited February 2017

    Dear George,

     

    Please find the image attached for the results getting from my side. 

     

    Thanks

    RAM

    <?xml version="1.0" encoding="UTF-8"?>Contour & plot.JPG

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