Learning Forum

[Goddy]

Hello, 

I performed a topology lattice optimization earlier. And I want to use material designer to determine the elastic properties of the lattice optimized region.

When I open the material designer analysis system and try to import the geometry, I get the error "Design in the current session use small units. Start a new session and switch to standard units".  I read from the following thread https://forum.ansys.com/forums/topic/material-designer-introduced-in-19-2/ how to fix this issue, but going to file>spaceclaimoptions>units the only unit options i see millimeter, centimeter and meter. So i can't change my RVE to small units.

Can anyone help me how to get around this? I'm quite new to using material designer so any tips will be great.

Thanks

[Sandeep Medikonda]

Hi Goddy,

What version of WB/SpaceClaim are you using? I would recommend trying the latest version (2019R2). 

Can you post snapshots of the workbench workflow and the error. You should still be able to use millimeters in your entire workflow.

Also, I don't quite understand how you are using your lattice optimization results?  Wouldn't you've variable lattice densities? 

Regards,
Sandeep

[Goddy]

I'm using 2019 R1.

Find the screenshots below:

The region labeled lattice structure is what I'm trying to to use material designer to get material properties. And that section has been topology (lattice) optimized.

Initially when I try to copy and paste the geometry into material designer, nothing gets pasted instead I get the error "Cannot paste geometry from standard unit design into a small unit design". So I change the units from micrometers to millimeters and try to paste the geometry again. This time, the geometry now appears, but I get this error message "There is no body"

So you might be right about the variable lattice point and maybe that's why I'm getting the error but let me try to explain something. I have done lattice optimization and tried to do the validation but i keep on getting errors (which I think has something to do with the lattice structure) which I can't seem to figure out https://forum.ansys.com/forums/topic/solver-pilot-warning-error-meshing-error/. So I thought maybe I can get around this issue by determining the mechanical properties of that region then solving the geometry now as a full solid (not lattice and solid as it is now) with 2 regions of different material mechanical properties.

Thanks for your previous response. Hopefully we can figure this out. Please I will appreciate any further help from anyone.

Regards,

Goddy

 

[Sandeep Medikonda]

Goddy,

I am not sure if I can resolve all the errors without looking at the model but you cannot use the whole part as an RVE. You are also trying to bring in STLs into material designer which again is a problem. Periodic meshing on such complex parts can also cause trouble...

If you want more control (i.e., have the ability to work with STLs etc), try running an FE model like jason suggests here. You would've more control and can debug better. Material designer is running the MAPDL solver in batch, you can see how it is setting up things by looking at the ds.dat files generated in each run.

Regards,
Sandeep

 

[Goddy]

 Thanks Sandeep for your suggestions. I tried what Jason suggested already, but I think it was too computational expensive. I got some error that didn't make much sense to me so I tried to change paths.

Basically the question I'm asking is similar to what was asked here https://forum.ansys.com/forums/topic/question-about-lattice-optimization/ and you suggested material designer can be used. But I can't seem to figure it out.

And also now redoing the lattice topology optimization because i changed the constraints etc. I am getting the error "error while trying to use density attributes" I don't know where this error comes from now. I had done the lattice optimization before with no errors.

So in short can I use material designer to get the young's modulus of the lattice optimized part and if yes, how do I get around the STLs you seemed to suggest that might be a problem (It's not the whole part which is the RVE but just a part of that geometry). Also any suggestion on why I'm now getting an error when trying to use density attributes for the lattice optimization. Or do you want me to attach the project file as an archive so you see what I'm saying better.

Regards,

Godlove