Geometric nonlinear - implicit

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

Hi,

 

Is possible to perform Geometric nonlinear - implicit with Gravity load?

 

because getting ISTOP=0 error.

 

 ENGINE ERROR:
  ** ERROR : RADIOSS IMPLICIT STOPPED DUE TO LOADING DATA **

 

Thanks

Narasimhamurthy

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Answers

  • Simon Križnik
    Simon Križnik Altair Community Member
    edited February 2019

    Hi,

     

    of course it is possible. Can you share the model for debugging purposes?

  • narasimhamurthy
    narasimhamurthy Altair Community Member
    edited February 2019

    Hi,

     

    this is confidential model . so i can not share. 

    please find attached .output file.

     

     There is friction coefficient between sheet metal and concrete. 

    please share possibility of error.

     

    Thanks 

    Unable to find an attachment - read this blog

  • Simon Križnik
    Simon Križnik Altair Community Member
    edited October 2020

    Looking at the .out file it is not obvious what the issue is. It is difficult, if not impossible to debug without the model. Perhaps you can share it with Altair support team through secure dropbox or Altair Connect.

     

    Theses topics had the same issue:

    https://community.altair.com/community?id=community_question&sys_id=5486883a1b2bd0908017dc61ec4bcb60

    https://community.altair.com/community?id=community_question&sys_id=7886883a1b2bd0908017dc61ec4bcbe5

    My best guess is first try to run without friction.  Then activate the nonlinear expert system to aid in the convergence of small displacement nonlinear problems with analysis>control cards>param>expernl>yes or CNTSTB. Description from Optistruct Help:

     

    YES

    Activates a nonlinear 'expert system' that aids in the convergence of small displacement nonlinear problems (NLSTAT). This version is designed to facilitate obtaining converged, high accuracy solutions without much concern for computational time. The system monitors the convergence of nonlinear processes and, if needed, implements measures designed to improve convergence for poorly converging cases. These measures include: performing additional iterations, under-relaxation, automatic adjustment of the load increment, as well as backing off to the last convergent solution and retrying. This may lead to a large number of nonlinear iterations for poorly converging problems.

     

    CNTSTB

    Additionally introduces temporary stabilization on contact interfaces (CONTACT or GAP(G) elements) that may improve nonlinear convergence, especially in cases where individual parts lack full support and are supported only by contact. The stabilization is applied only during incremental loading and is not present in the final solution for the respective nonlinear subcase. (Refer to the CNTSTB Bulk Data Entry for default and priority information).

     

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

    FYI, Post HM 2017.2.4 relevant nlgeom loadstep panel have been removed.Change the analysis type to Nonlinear Quasi-Static(NLSTAT) from NLGEOM and add the below card

    PARAM,LGDISP,1

     

    NLOAD is not valid in NLSTAT, you can directly apply enforced displacement through SPC/D card

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