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Nonlinear Optimization with Contact

Hi,

Due to contacts in my model I wanna let my optimization run nonlinear. So far the linear analysis and optimization works. To let the analysis and optimization run nonlinear I created a load collector with the card image NLPARM. Additionally I created a non-linear quasi-static loadstep. The nonlinear analysis gives me results where as the optimization does not give any result even though I can let the optimization run without any error.

Here I'm uploading a very simplified model that is compatible to the HyperWorks student edition. The contacts are not implemented yet. But there should be contact between the green, the yellow and the blue component. Maybe someone can tell me by which criteria I have to decide if the contact partner is master or slave.

I'd be glad to get any advice how I can set up a nonlinear optimization with contacts in Optistruct. My question is: which steps do I have to carry out to turn a linear into a nonlinear optimization. Unfortunately I couldn't find that much information about it.

Felix

P.S. The model shows a medical implant for connecting bones. Maybe someone is wondering what it is /emoticons/default_wink.png' alt=';)' srcset='/emoticons/wink@2x.png 2x' width='20' height='20'>

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Merula_20758

Your steps seem right to me at first glance. Can you provide a model with the contact enabled so I can try something on my end ?

Have you tried doing a generic loadstep? This once helped me.

As well it would be good to know what you mean with no results. Is there no _des.h3d ?

Best regards,

Merula

Altair Forum User

Hi Felix,

You can consider the softer material as slave and harder as master.

The steps to turn a linear to non linear analysis depends on which type of non linearity you are interested in .

If you have material non linearity involved, you have to included non linear material properties using MATS1 card for example.

Altair Forum User

I am doing nonlinear analysis with contacts (Analysis type: Generic). I have the test data (excel sheet) of 172000 points, displacement vs time. I am applying it using Tabled1. In NLOUT I asked for 100 output, but in the results there is no effect as it is not considering all the data points. Then I tried with 172000 in NLOUT, but it is taking a lot of time to run. Please help me. How can I perform the analysis.

I am allpying the load on centre of crossmember of truck chassis and want to get the output on toolbox.

Thankyou.

Altair Forum User

Hi Akhil,

What do you mean by not considering all Data points?

Data points on TableD1 has nothing to do with NLOUT output, I guess.

Altair Forum User

I mean there are no stresses on the toolbox, when I take NLOUT=100 and in input I used Tabled1. The model is converged but nothing on the toolbox.

Rahul Rajan_21763

NLOUT card is new from v14.

NLOUT – Controls the incremental result output for Small Displacement Nonlinear Analysis and Large Displacement Analysis

Try with NLSTAT loadcase.

Altair Forum User

I mean there are no stresses on the toolbox, when I take NLOUT=100 and in input I used Tabled1. The model is converged but nothing on the toolbox.

Hi,

Is it possible to share the model file and .out file with us?

Use the file transfer link available in my signature below to share the model files.

Altair Forum User

Hi,

I have shared the model and .out file. Please check.

Thanks.

Altair Forum User

@Akhil Mehndiratta

Thank you, I will check and update to you soon.

Altair Forum User

Hi Akhil,

Can you remove SPCFORCE output and try again?

Altair Forum User

Hi,

I have changed few things and shared the model and .out file. It is not converged. Please check.

Thanks.

Altair Forum User

Hi Akhil,

From the out file I can see that with upto 99% load the model converged.

Can you reduce the load a little bit to upto 99% and check if you are able to see the results.

Altair Forum User

Hi,

It is not converged even after reducing the load to 50%.

Thanks.

Altair Forum User

Hi Akhil,

I will check the model and will get back to you.

Altair Forum User

@Akhil Mehndiratta

Run the shared file and check if that converges.