# Shape (?) Optimization for 1D Elements

## Recommended Posts

Hey guys,

I was wondering if it is possible to setup the following optimization problem.

Lets say I have a set of nodes and bar elements. This framework has some loads and boundary conditions.

I am not sure if the node position of each node is optimal regarding compliance.

I would like to define "shapes" for the nodes where I can set some pertubations e.g. Node x can move in a sphere of radius y.

I have not seen this kind of optimization although I think it must be possible from an algorithmic point of view. Any suggestions?

Thanks!

##### Share on other sites

Hi @Merula  This sounds interesting.  I am going to try this and I will update you soon.

##### Share on other sites

Much appreciated!

##### Share on other sites

Some update:

I tried with a simple beam but the node movement is not following the spherical/cylindrical coordinate system.

I will share my latest findings soon.

##### Share on other sites

It could also be a cube, if the spherical movement is the problem.

I just can't see how I can implement the optimization setup (i.e. the design variables )

Best regards,

Merula

##### Share on other sites

Trick here is I am realizing a 1D beam to 3D shape. So I am using 3D element grids for shape optimization.

##### Share on other sites

@Prakash Pagadala thanks. Can you show me how to realize this or send me a model file where I can see this?

##### Share on other sites

Do I have to use morph volumes for this? I would like to just simply define that each node can freely move in x y z within a certain range. Minimizing the stress is the objective. I share a model file, where I have a simple beam setup where I would guess that a symetric design would be optimal.

I stuck at defining the shapes.... I've learned that free shape is not possible because I have no 2d/3d elements

Best regards,

Merula

beam.hm

##### Share on other sites

You are right, shape optimization is not possible with 1D elements. You need to model as either 3D or 2D. So I created a 3D model with a layer of 2D skin and used shape optimization to accommodate all Dofs,

Unfortunately, I don't have the mode with me.

##### Share on other sites

I digged on this a little deeper and found a way to optimize 1d elements....

it is possible if you choose freehand under morphing and save the shapes after having changed the node positions.

Best regards,

Merula

##### Share on other sites

I agree, but whatever you get is a concept and this needs to be fine-tuned with gauge optimization, maybe?

Apart from that, the results need to be validated with 2D/3D elements, as the number of Dofs will be different.

The shape on optimization level is not supported for 1D elements.

##### Share on other sites

Yes, this is a concept as it does not change the shape of the actual 1d elements but the location of the linking points, but nevertheless important when you come from a topology optimization and want to fine tune the reconstructed results (when using simple bars for example).

A gauge optimization would be the final step.

Best regards,

Merula

##### Share on other sites

Hey guys,

what do you think of the result I got for the CClip.

I saw it is not a symmetric result although the input and loadcase is symmetric. Ignore the buckling constraint for now.

My question is: Is this procedure correct? The compliance is better than with topology optimization.

I attached the following results:

1) Input Deck of the topology optimization (modified version of the cclip tutorial): cclip1.fem

2) Result of the topology optimization (modified version of the cclip tutorial): cclip1_des.h3d

3) Input Deck of the Shape Optimization ShapeOptimization.fem

4) Result of the Shape Optimization ShapeOptimization_des.h3d

Best regards,

Merula

ShapeOptimization_des.h3d

ShapeOptimization_des.fem

cclip1.fem

cclip1_des.h3d

##### Share on other sites

Hi,

This looks pretty good. I see the results are better.

## Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

×   Pasted as rich text.   Paste as plain text instead

Only 75 emoji are allowed.