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Optistruct Material Non-linear analysis - facing high cutbacks due to large strain

Ashish_DhopeUser: "Ashish_Dhope"
Ashish_Dhope
Altair Community Member

Hi,

I am working on an analysis that involves high stress and strain in the material. I have assigned non-linear material with material curve defined through TABLES1 and assigned at MATS1 in the material.

following is the error I am getting:

image.png

I am using Optistruct as a solver. Can anybody help me with this? I have used NLPARAM(LGDISP), NLADAPT cards as well.

Thanks.

Ashish Dhope

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OptiStruct
v2024
Altair HyperWorks Platform
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    Marina_LimaUser: "Marina_Lima"
    Marina_Lima
    Altair Employee

    Hi Ashish,

    In this case, out file gives you a hint that the plastic strain is excessive, so it's good to review you material properties, specially MATS1.

    The subcase is almost reaching the end, 95% of the final load, so I recommend you to request on NLOUT the parameter SVNONCNV=YES to save the nonconvergent steps, because you would be able to load this results in HyperView and understand where the convergence is getting trapped - may be slippage, or even some part is not properly constrained.

    After checking the nonconvergent steps, if the issue seems to be contact stabilization, I would recommend you to try PARAM,EXPERTNL,CNTSTB parameter: https://2024.help.altair.com/2024.1/hwsolvers/os/topics/solvers/os/cntstb_bulk_r.htm?zoom_highlight=cntstb

    Best regards,
    Marina Lima

    Ashish_DhopeUser: "Ashish_Dhope"
    Ashish_Dhope
    Altair Community Member
    OP

    Hey Marina,

    Thanks for your reply. I altered the material properties - beyond UTS strain value kept constant. And this solved my issue. I will also try the SVNONCNV=YES to save the nonconvergent steps.

    Thanks & regards,

    Ashish Dhope

    Marina_LimaUser: "Marina_Lima"
    Marina_Lima
    Altair Employee

    Good to know, Ashish! If you can, please, accept the answer to help other users

    Best regards,
    Marina Lima

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