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Import Element definition

8 REPLIES 8
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Message 1 of 9
priyashanmugam
508 Views, 8 Replies

Import Element definition

Hi

 

Is there a way to import element definition (plate thickness) for plate/ shell elements when  importing CAD geometry from Rhino? Else, is there a way to read plate thicknesses from a file into element definitions for each part?

 

We often import CAD geometry built using Rhino into Autodesk Simulation Mechanical for FEA. Majority of our models are analyzed using plate/ shell elements. The part names defined in Rhino contain information regarding plate thickness (for instance, Rhino parts are named as ½” Main Deck, 3/8” side shell etc.). These part names are imported into ASM during model import. Sometimes, these models have parts in excess of 900. It is becoming very tedious to manually enter the plate thicknesses in element definition. Is there a way for ASM to read the plate thickness from the part name and assign it to the element definition. For instance, if a part is named <1/2” Main Deck>, and if the element type is defined as plate elements, would there be a way for ASM to automatically assign ½” for the plate thickness of that part during model import from Rhino, or by reading from some user defined file?

 

Kindly let us know if a solution exists for this problem in Autodesk Simulation, since the process of manual definition is tedious and time consuming.

 

Thanks,

Priya

8 REPLIES 8
Message 2 of 9

Hi Priya,

 

No, the software does not have the capability to read the part name, extract the thickness from the name, and assign that to the element definition. But it should not be too difficult to write a program that would do that. The easier method would be something like this:

  1. Import and mesh the model.
  2. Translate the model database to text files. "Tools > Options > Database Translation".
  3. Open the translated file "model.csv" in Excel.
  4. Write a macro in Excel to search for the part names, extract the thickness, and write that to the element definition. While you are at it, you would want to write all of the other information that the element definition creates, too. (Maybe the material properties if they are known.)
  5. Translate the text files back to the database format: "Tools > Options > Database Translation".

Its also possible to read and write to the model database directly (model.dbf), but that requires more work. (Specifically, it requires being able to read/write a Foxpro database -- which is largely if not entirely undocumented. I have done it in the past using Visual Basic 6, but it was many years ago.)

 

I'll mention another feature that the software does have. This may not work for your current situation, but it is nice to know about. You can save all the part information (color, element type, element definition, material properties) from a model to files, and then read those files in a different model. This works well when you have similar CAD models and want to get all of the part information from one completed analysis into a new analysis model. You do this by right-clicking on a part (or parts) and using "Save Part Attributes to a File".

 

 

Message 3 of 9

Great suggestion John! I can attest, reading and writing FoxPro databases is not something I'd recommend.

 

One other method, thats not as automated as John's suggestion is to use the copy/paste feature in Simulation Mechanical. One can copy the element definition, element type, color, or material from any part in tree view of the FEA Editor and paste it to one or several other parts. You can select multiple parts by control-clicking or if you have a large number of parts that are the same thickness group together you can use shift-click. Then simply right-click and select Paste: element definition/element type/color/material/all attributes.



Andrew Sartorelli - Autodesk GmbH
Message 4 of 9

Thanks, John. That was helpful. I'll try doing that.

Message 5 of 9

Thanks, Andrew. The multiple parts selection method is what we are currently adopting. However, it still takes significant amount of time to comb through the list of parts in the part tree and choose parts with similar thicknesses, not to mention the high chances of making a manual error in the process. It would be more reliable to automate the process. I'll try John's suggestion and see if I can get success.

Message 6 of 9

Hey John,

 

I've tried your method with a very simple model imported from Rhino:

 

I've modeled a cube with each side being its own surface object in Rhino. Each object is named in rhino using the following convention : XXmm Description. 

I imported the model in to ASM 2015 and meshed it. I then went through your steps described above, I can see in the "Model.csv" file where the part thicknesses are assigned values. I do not, however, see the part names anywhere in this file. Are you suggesting that we import the part names from another source?  If we are to find the part names somewhere else, how are we supposed to match the part names to the part numbers assigned by ASM?

 

This brings up another issue, and if I'm hijacking the thread I'm sorry, I could start another if that would be better. What is the convention for assigning part numbers to objects in a Rhino model? With this simple cube model, I have modified and re-imported a few times trying to find the pattern, but it does not seem to be a simple answer. Some predictability here could help me create a smoother workflow. 

 

Best,

David

Message 7 of 9

Well, that certainly adds a wrinkle to the idea!

 

I did a test and agree with your findings - that the part name is not in the model.csv file to begin with. After I did a "Check Model", the part names were added to the model database! (The variable name is "Egroup(i).General.Tag", where i is the part number. The name appears in either column 2 or 3. I think the length of the name affects which column it appears in.

 

Sorry for these complications. It seems like a lot of work to add dummy information into the element definition (and materials) so that you can do a check model so that you can get the part names! I then thought about generating a report to get the part names, but appears that a part does not appear in the report unless the part is complete. (That makes sense.) By the way, the part names are stored in the .FEM file (I believe), but I am not aware of any way to read the fem file to get the part names. That's why I suggested the model database (not knowing that the names are not added until after a Check Model.)

 

Dare I suggest trying this?

  1. Can the Database Translation utility be automated to convert from the native dbf to cvs?
  2. Use automation to enter dummy element definition and material properties.
  3. Can the Database Translation utility be automated to convert from cvs format back to the native dbf?
  4. Use automation to do a "check model".
  5. Now that the model database has the part names, convert from the native dbf to cvs.
  6. Use automation to update the part thickness with the real data based on the part name.
  7. Convert from the cvs to native dbf.

(You could ask someone from Autodesk tech support about the steps to automate the database translation utility and doing a check model. These may even be covered somewhere in the discussion group.)

 

Another thing to watch out for. All numerical input is stored using the model units. Please check what the model units are after importing a Rhino model. (The model units are the first entry under the "Unit Systems" branch in the browser.) So if your part name is "3mm sidewall plate", you need to make sure that the model units are mm. It's quite possible that the model units are something else, such as m. This will add another complication to the process!

 

Good luck.

 

Message 8 of 9

John,

Officially Autodesk doesn't provide support for automation since there is no official API or scripting language for the Simulation Mechanical. I will check with some folks in Pittsburgh to see if I can get any information about possible routes for automation because I think this is an interesting project.


Andrew Sartorelli - Autodesk GmbH
Message 9 of 9

After some internal discussion, I have been given permission to provide a sample script that was generated by one of my support colleagues. This script is not officially support by Autodesk, Autodesk Technical Support can not provide any guidance outside of the forums, and I make no promises that I will be able to answer specific inquiries related to the script. Please use this script at you own hazard and back up any an all information before attempting to use the script on a file, Autodesk will not assist in repairing damaged files.

 

Now that I got all that out of the way! This script was generated to workaround an issue that popped up in Simulation Mechanical 2015 R1 where you can't modified the load case of a nodal or surface moment in Linear Static Stress. The script looks for LC=## in the start of a load's name, the load case for the load is then modified to be ##.  To access and specify the analysis file modified by the script, open the file in Excel, go the View tab, select Macros, Edit, now change strFileName to the complete file path.

 

To run the VBA application, one will first need to alter your computer's "PATH" environment variable.  This can be accomplished by accessing "START" on your desktop, then right-clicking on your computer name and choosing "Properties".  Choose "Advanced system settings" from the left margin, then choose the "Environment Variables" button.  Select "Path" from the "System Variables" and choose the "Edit" button.  Go to the end of the variable value, and type the following:

 

                ;C:\Program Files\Autodesk\Simulation 2015\

 

In the coming days I hope to provide some more detailed information

 



Andrew Sartorelli - Autodesk GmbH

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