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Zdeny

Topology and lattice optimization results - CAD interpretation

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Hello,
I would like to ask you about the software which you use for processing the results from OptiStruct topology optimization because OSSmooth does not provide CAD files good enough for manufacturing. Do you think that is good to make FEM reanalysis without surface remodeling? Does it provide valuable information about the structure? And how do you recommend working with lattice optimization? Because many of the optimized BEAM elements aren't 3D-printable. Is there any experienced workflow how to get a printable CAD file?

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Guest

Hi @Zdeny

 

OSSmooth with lattice activates the smoothing process before the generation of the lattice. One can also provide a target mesh size to achieve desired results. During second phase the beam elements are sized to the bounds and are resulted lattice structure is ready to print.

 

The best path for 3D printing for now is to use 3-Matic from Materialise to read .fem file of the lattice result. Altair Inspire does has a feature which generates lattice CAD and soon it should be available with OptiStruct

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Thank you for youe reply @Prakash Pagadala,

I know that OSSmooth smoothes the surface before the generation of the lattice structure. You say that I can influence the lattice structure size with activating the remesh, do I understand correctly? But i have a few questions.

 

1. If I use this smoothing process in OptiStruct will I get as smooth model as in the picture below?

 

2. If I use OptiStruct FEM reanalysis for the obtained *lattice_optimized.fem or just *topology_optimized.fem file will the results obtained from the analysis be valuable? Because surface topography does influence the FEM analysis results, doesn't it?

 

3. So do you recommend to use OptiStruct for topology+lattice optimization, then smoothing it in 3-Matic (I will get printable model) and after that export the *.fem file back to OptiStruct for the reanalysis?

 

image.png.78574496e3d99cc343f5a25440e13f13.png

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Hi @Zdeny

 

I have shared a mail with a PPT and a tcl script, A new feature in OSSMOOTH which allows for the use of two thresholds (void to lattice and lattice to void). OSSMOOTH will then output a set of elements that represent lattice and one that represents solid. It also removes the void. The transition between lattice, void and solid is smooth.

 

Then you can use the new unit cell feature (DLATTICE/CELL) to fill the lattice region(s). The attached ppt explains this too and may require some manual work. 

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@Prakash Pagadala

Thank you for sharing the script with me.

 

The script doesn't work for me (error message). I'm a beginner in this field so excuse me but I really don't know how to script and what do those 2 lines mean in OptiStruct language so I'm not able to do it by myself.

 

I also have another questions:

a. I haven't tried to export *lattice_optimized results yet. Could you please tell me what type of "lattice_file" can I export (.STEP or .STL file)? Will the result file contain an information about the optimized lattice struts (information about its diameters)?

 

b. Is it possible to create your own lattice cell type and import it into HyperMesh?

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16 hours ago, Zdeny said:

The script doesn't work for me (error message). I'm a beginner in this field so excuse me but I really don't know how to script and what do those 2 lines mean in OptiStruct language so I'm not able to do it by myself.

 

Can you share the error message, please?

 

16 hours ago, Zdeny said:

a. I haven't tried to export *lattice_optimized results yet. Could you please tell me what type of "lattice_file" can I export (.STEP or .STL file)? Will the result file contain an information about the optimized lattice struts (information about its diameters)?

If it is for 3-matic, you can export to .fem with long format type.

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ad a.

image.png.dab764c4e21a446cc32c8a993a8ff5e8.png

ad b.

No it's not for 3-Matic because I don't have access to 3-Matic. That's the reason why I'm asking about STEP or STL file.

 

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Hello @Prakash Pagadala

Thanks for your reply. I made a mistake. So I should perform topology optimization with POROSITY=HIGH checked (in LATPRM) and then I will obtain a design with more medium dense regions, right? At this point i will have a *.sh file with density results. I now I can Import this file into HyperMesh using OSSmooth and setting threshold, for example 0.1 which will remove the elements below this density. But now I don't know how to create the "solid phase set" and "lattice phase set" with smoothed surf between them, I'm sorry. Could you please help me?

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Hello, I am performing a study on a lattice optimization where I compare the two designs, the first design being from a DTPL + Lattice Optimization and the second being defining a unit cell using the DLATTICE card. I am having a hard time creating this card manually and also referring it to a CELL card which defines my unit cell. I already looked through the help documents but I still can not figure it out.

 

Any help would be greatly appreciate.

 

Thanks, 

Wesley 

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On 10/8/2018 at 12:37 AM, Guest said:

Hi @Zdeny

 

I have shared a mail with a PPT and a tcl script, A new feature in OSSMOOTH which allows for the use of two thresholds (void to lattice and lattice to void). OSSMOOTH will then output a set of elements that represent lattice and one that represents solid. It also removes the void. The transition between lattice, void and solid is smooth.

 

Then you can use the new unit cell feature (DLATTICE/CELL) to fill the lattice region(s). The attached ppt explains this too and may require some manual work. 

Hello,
Can you please share  with methe PPT and tcl script file, that you mentioned.

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