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Symmetry Constraint in Size Optimization

Gokul Ramarathnam_20422

Hello,

I am working on design optimization of an aircraft component. I have obtained the shape of the required object using a topology optimization and am interested in refining the thickness of the part using a Size Optimization.

However, I am unable to find an option to create a plane of symmetry in the DESVAR card or any other location. The results obtained from the optimization show a density distribution that is not symmetric either. Is there anyway to do this?

Please let me know.

Thank you!

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Altair Forum User

Hi,

Yes, there is no option to enforce symmetric with size optimization.

Let check if there is any workaround for the same.

Gokul Ramarathnam_20422

Hello Prakash,

I did not find any other option but I think the extrusion maintains a semblance of symmetry on its own.

Thank you for your help!

Altair Forum User

Hi Gokul,

Extrusion in topology?

I think we are talking about size optimization. If at all you are interested in topology, there is the symmetric constraint.

Altair Forum User

Hi Prakash,

I've searched everywhere on how to set up symmetry plane for topology optimization. I found one but I'm not sure whether this is right. For example if I have xy plane as a symmetry plane, all the nodes on the plane should be constained to no displacement along z, no rotation about x and y? Please tell me how to do it.

Altair Forum User

Hi @Izzdham Shah

I am sorry for not being clear.

You can download OptiStruct Optimization ebook which has all information and how to do stuff https://altairuniversity.com/free-ebooks-2/free-ebook-practical-aspects-of-structural-optimization-a-study-guide/

<?xml version="1.0" encoding="UTF-8"?>

Hi Izzdham Shah,

what you have described is the correct way to set up symmetry boundary condition.

However, symmetry plane for topology optimization refers to a concept in optimization called Pattern Grouping where optimizier is forced to produce symmetric design even if loads and BCs are asymmetric.

Altair Forum User

Hi Ivan and @Izzdham Shah

Just to make it clear, the symmetric pattern in topology is a manufacturing constraint which enforces solver to find a symmetric design or close even the loads and BCs are not symmetric.

In order to set the symmetric analysis, you need to do that with BCs. No displacement normal to the line of symmetry...

Altair Forum User

Hi, @Prakash Pagadala and @Ivan,

Thank you for the replies. Now I'm clear about the pattern grouping concept in topology optimization. But still confused on how to apply it in my model. Referring to the picture of my model below, I just want to use half of my design space and use symmetric constraint (the white nodes, YZ plane) to produce similar pattern on the side. So when I make a full model and apply the same load, it would produce just the same result as this model. Here, I set up the symmetric BCs on the nodes on symmetry plane. But according to what you have said, this seems wrong. Do I need to make a full model and apply pattern grouping in the middle or is this a correct technique of doing it?

Help1.PNG.00ce6bdb183a9f27631e19f040f8bbdc.PNG

Thank you.

Altair Forum User

Hi,

If you can enforce symmetric boundary conditions to model one part of the model, you do not need to use symmetric option. Symmetry option in topology optimization is used when the model has unsymmetric mesh or loads and wants to enforce symmetry about a given plane(s)

Altair Forum User

Hi, @Prakash Pagadala
My name is Lalo we are trying to set up an static stress as a constrain, and at the same time minimize the mass , and we have the next output What can we do?

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Hi,

I am able to run the file as it is.

Can you please update your HyperWorks solver and try again?

Altair Forum User

Hi,

I am able to run the file as it is.

Can you please update your HyperWorks solver and try again?

Thank you very much, We ran it again and it gave us the same result. We´re using version 13. And We run it as optimization. What version do we need to use to solve it?

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

HI,

Not sure if you had shared the same file with me or not, but I don't see any stress response in the file you shared.

Can you share the file with stress response?

Please use this link to share the files: https://ftam1.altair.com/filedrop/~Ce4god

Altair Forum User

HI,

I think the error is because of the beam section. Please use Standard OptiStruct beam section type for optimization and try again

<?xml version="1.0" encoding="UTF-8"?>

HI,

Not sure if you had shared the same file with me or not, but I don't see any stress response in the file you shared.

Can you share the file with stress response?

Please use this link to share the files: https://ftam1.altair.com/filedrop/~Ce4god

Thank you for your answer.Hello we are in trouble again.We Want to make an optimization response as /static stress/ of 1D PBEAML type. But when we select the elements don´t give us von mises stress as a response only normal.
We´ve tried to do the same with and small model and it works. What is wat can we do?

We want to optimize an structure with diferent values of stress constraints throug the y axis so that is the reason why we are interested in extract the von mises stress in different collectors.

Thank you for your answer.Hello we are in trouble again.We Want to make an optimization response as /static stress/ of 1D PBEAML type. But when we select the elements don´t give us von mises stress as a response only normal.
We´ve tried to do the same with and small model and it works. What is wat can we do?

We want to optimize an structure with diferent values of stress constraints throug the y axis so that is the reason why we are interested in extract the von mises stress in different collectors.

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

HI,

Please update your HyperWorks software.

<?xml version="1.0" encoding="UTF-8"?>

Thank you @Prakash Pagadala /emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20' />

Hello We've sent you another question, could you answer that please.

Altair Forum User

Hi,

I got your questions, give me some time to come up with a plan on how to do it the best way /emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20'>

Hello Prakash Pagadala

we´ve been working with the model of honeycomb strucuture. Why this model y so flexible, and what has happened with the energy curve because the don't apeear?

What can we do?

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Hi,

I got your questions, give me some time to come up with a plan on how to do it the best way /emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20'>

Do you want to change the shape or just the element thickness?

If the shape of the cell is the target, you need to define multiple shape variables with multiple bounds.

Altair Forum User

Hello Prakash Pagadala

we´ve been working with the model of honeycomb strucuture. Why this model y so flexible, and what has happened with the energy curve because the don't apeear?

What can we do?

There is no TFILE in ENGINE and that is why you don't see any curve.

Can you try with ISOLID 24?

<?xml version="1.0" encoding="UTF-8"?>

Prakash Pagadala

I will try

Hello, we are trying to make a drop test, but the rigid body dones't stop when it get contact with the rigid wall
Whan ca we do?

The normal direction is right but we don´t know how to solve this.

I can share my file to you, in ordert the solve this problem.

https://ftam1.altair.com/filedrop/~Ce4god

i sent some files.

Hi,

Mr. Prakash Pagadala is not a member of the Altair academic team anymore (his account was deleted).

From Radioss>Frequently Asked Questions>Kinematic Condition

2

Since a rigid body controls the movement of its slave nodes, a rigid body slave node can not use another condition (specifically it cannot belong to another rigid body).

If flag Ikrem of the rigid body gets its default value =0, the slave nodes of the rigid body are automatically suppressed of the rigid walls; the master node of the rigid body will realize the contact with the rigid walls if it is declared as a slave node of the rigid walls.

thnaks

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