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Optistruct composite analysis (failed output results)

Hi,

I'm have to run a composite optimization with Optistruct and so I followed all the tutorials set-up steps, but at the point of running the static analysis the results that I obtain doesn't make any sense (displacement 411 cm...). I imagine it could be a problem of units but I've checked them and I cannot find out where the problem is. I've had defined the 'DTI_UNITS' card with the units Kg,N,mm,s and I've also set all the values introduce into these units. Even the value of the G force applied is -9810 (mm/s²). So I really don't know where the problem comes from.

I send attached the output file results. If you need any other information to help me solving this, tell me please. Thank you very much in advance.

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Altair Forum User

Hello,

For a static analysis, i dont think dti unit card doesnt really has an effect.

Maintain unit consistency in your model and try again

Altair Forum User

Hello,

I've changed just the units of the G force from 9810 (mm/s²) to 9.81 (m/s²) and maintain in Kg,N,mm,s all the other values (material properties, etc). Now the results are good. Is it ok that the G force is in m/s² while the other values are in mm?

Thank you for your answer!

Altair Forum User

Hello,

You can calculate for your self /emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20' /> using F= Ma.

Newton= Kg* m/s^2. So what you are using makes sense.