Changing height of DesignSpace during optimization
Altair EmployeeHi, I have to optimize the natural frequencie of a component and got for this task a nearly unlimited design space. Only at the top and bottom of the part has to be Connections (plates), so there are nondesign spaces.
To get the optimum in the topology optimization the design space is as big as possible, but with this optimization Optistruct calculate only the optimum in this design space, because the two nondesign spaces at the top and bottom are fixed.
So there is also the possibility that the optimum is somewhere between. To consider that my idea is to use two optimizations like topology and shape.
I have not found a solution how to change the height of my design space with shape optimization. I think Optistruct have to get a start value for example 40mm and an increment like 2mm so it can calculate all Options in any height. Furthermore for this example OptiStruct have to mesh the Designspace every time it Change the height again and automaticaly because otherwise it press the Elements to much togehter.
Is that possible or do you have any other ideas?
Thank you very much!
Answers
-
Hi @B. Foerster
You can use Move limit available in Shape optimization panel
Altair Forum User said:Furthermore for this example OptiStruct have to mesh the Designspace every time it Change the height again and automaticaly because otherwise it press the Elements to much togehter.
If at all the optimization runs into element quality error, you can use DOTPRM>>REMESH which meshes the model at current iteration to improve the element quality,
<?xml version="1.0" encoding="UTF-8"?>
0 -
You can learn more about Move limit adjustments on OptiStruct help.
0 -
Thank you very much for your answer. It was very helpful, but I've got a new problem.
My model runs into element quality error, but I think I've Setup the remeshing process with Optimization>>opti control>>set REMESH to 1
<?xml version="1.0" encoding="UTF-8"?>
What I have to do to run the optimization without element quality error?
0 -
Hi,
Can you share the .out file, please?
0 -
Of Course. Thanks for your fast reply
0 -
Hi,
Can you add PARAM>>CHECKEL>>NO and check if this helps?
0 -
I've tried it but it comes again the same error... Do you have any other ideas?
0 -
The error message you got shows that the model failed in the element validity check and the FEA solver cannot process the simulation on the model with such poor element qualities. To fix this error, you may have to find the bad meshes and remesh that area.
0 -
My modell has a Topology and a Shape optimization. If I delete the Shape optimization it runs totaly normal so it's not the Problem of the bad mesh at the beginning. Something is wrong with the Shape optimization.
In the Outputfile stands: 'Total # of elements that failed validity check (error) =530462'
This Elements who failed are all the elements of the part who has to change his shape and it is'nt possible that they are meshed all wrong from the beginning
0 -
Hi,
I can see from the out file that optimization is not started and element quality started failing even before optimization,
0 -
I think I got it. The initial Value in the Shape optimization was set to the upper Bound
0 -
The optimization runs, thank you very much Prakash.
But I'm not very happy with the results because it seems like OptiStruct ignore the topology optimization.
In my mind I hope that Optistruct takes at first the normal Shape of the part, starts the topology optimization through all iterations. After that it makes the DesignSpace a little bit smaller and starts the topology optimization again and so on. Optistruct should do that till it arrives the smallest Shape.
Do you think it's possible to realize that?
0 -
I am sorry, but I thought you are doing a shape optimization but not a topology.
Topology optimization will alter the material density (removes materials) but I don't think it will have much effect on the shape.
0 -
That means it is not possible to integrate Shape into Topology Optimization?
0 -
HI,
It is possible but the repeated sequence, I need to check.
I will get back to you soon.
0 -
Altair Forum User said:
The optimization runs, thank you very much Prakash.
But I'm not very happy with the results because it seems like OptiStruct ignore the topology optimization.
In my mind I hope that Optistruct takes at first the normal Shape of the part, starts the topology optimization through all iterations. After that it makes the DesignSpace a little bit smaller and starts the topology optimization again and so on. Optistruct should do that till it arrives the smallest Shape.
Do you think it's possible to realize that?
Can you share the .out file for this, please?
0 -
I have some other problems with my model, when I am ready I will come back to it, thank you very much
0
