Optistruct


Hi,
I wanted to check, when I run optistruct for topology optimisation, I receive a message after 30 iterations that maximum iterations has reached, and design is infeasible.
What do I do from here, Can I increase the number of iterations.
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Hi Prakash,
Thank you for helping me, also I was told to do UNIT CONSISTENCY CHECK.
How do I do that?


Hi,
That is you have to take care. Maybe the below can be a little help for you...




Hi,
What is the unit system you are using for your model?


I can see a huge violation in constraint values. Can you please explain on how do you came up with compliance constraint values?
FYI


Hi Prakash I did an analysis on the previous bulkhead that was designed, and from the out. file I found these constraint values


Hi,
I am attaching the files that I got this information from


The forces and length are in N and mm, while the material young modulus is in MPa, and density is in t/mm^3.
Is this something that I am doing wrong, also how do I set which units I want Hypermesh to be in.


Hi Prakash,
I think my units were not correct. I changed my units, and I ran the optimisation again. I believe that I am getting close to the results but I am not sure. I still need to make improvements and if you have a look at the attached files and tell me what I could do to make it better. I think I should use the draw or extrusion function but I don't know how to use them properly.
Regards,
Sufian


Well, I was trying with volume fraction and compliance with extrusion. I got some results.


Hi Prakash,
Can you tell me how to use the Draw and Extrusion variables, I don't understand how to use them. If you can make a video or something.


Also the results you got, was it from the latest files that I uploaded?


Go to Extrusion panel and select the node path along the thickness of the component.


Do I select twist or no twist, and then it asks me. For the no twist it is only primary path but for twist it is primary and secondary.


Instead have a weighted compliance response as objective and volume fraction as constraint.


But then I don't know what value to put for the upper bound for volume fraction.


Hi Prakash,
This is the result I got from using Mass fraction as objective and Compliance dconstraints. I used extrusion with twist.


Can you keep the iso contour threshold value to say 0.3-0.4 and see the results?
Also, why you had twist for extursion, I dont see any twisty shape in your model. So having twist may not help in your case.


Goto Iso panel (shown in red in the image below) and change the value.


I did it with no twist and also with Draw option. But why is it removing material from


I set the threshold value, and this is extrusion with no twist. But again why is it removing material from those areas.


Also this is the result I am getting with the Draw option. I uploaded a picture of the front and back view. Why are they different?


Try this:
1) Have Weighted compliance as objective and volume fraction as constraints (upper bound say 0.6 and lower bound 0.3)
2) Have a minimum and maximum member size in your topology model (topology>> Parameters)




What values do I put for the minimum and maximum member size, and with these parameters should I use extrusion.


MINDIM atleast 3 times the average element size and MAXDIM should be 2 times the mindim.
Yes you can use extrusion.


By element size do you mean the mesh element size? Because in that case my mesh element size 4, so my MINDIM will be 12 and my MAXDIM will be 24


Hi Prakash,
This is the result I am getting when using parameters. I set MINDIM to be 12 and my MAXDIM to be 24.
Hi SUf92,
Please refer to the below Tip and Trick:
http://www.altairuniversity.com/wp-content/uploads/2015/10/Design-iteration_increase.pdf