Subcase convergence till 0.99 of load in SimLab (OptiStruct)

Question

Hello,

i'm pretty new in

OptiStruct solver and can anyone help me with my case please? The loadcase is

converging only till 0.999998 of load.

Is there any way how

it could continue (load scale or something similar) from LoadCase 1

(Pretension) which stopped on 0.99999 (depends on DTMIN) of load to LoadCase2.

Or if you can help me where can be the problem (I assume problem is in

contacts), if there's some common situations or settings in which this problem

occurs.

Let me know if you want more details and description of the model from my side.

Thanks a lot for any help.

David

Rajashri_Saha · Answer

Hi David,

My suggestion is to add CNTSTB (Contact stabilization) card in loadstep with S1=0.01. This helps convergence when there is cutback towards the end of loadstep with contact nonlinearity.

Thanks

Rajashri

Joachim_B · Answer

Hi David.

Based on your informations, I can't determine the problem, but you probably have a contact issue.

Did you generate a result from the unconverged load case? Do the results look plausible?

What I can recommend to you is this community post. Several convergence issues are described there, along with solution and analysis suggestions. With that, I have been able to solve all my convergence problems so far. The post Convergence Issue #2 should be relevant for you.Joachim

https://community.altair.com/discussion/39803/troubleshooting-for-optistruct-nonlinear-convergence-issues