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

Ashish_Dhope · 2025-05-20T15:04:14+00:00

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Ashish_Dhope

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:

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_Lima

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_Dhope

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_Lima

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

Best regards,
Marina Lima