topic Re: Imported shell model analysis in Inventor Forum

Imported shell model analysis

Anonymous — Mon, 12 Jan 2015 21:19:54 GMT

Hi,

I have a brief experimenting encounter with Inventor and I am trying to import a Solidworks shell based model (using Solidworks, stp or parasolid yields the same result)

The geometry imports as a single surface body, without any reported errors. However when I try to run an analysis on it, the software refuses to interact with the model; and furthermore complains that the model contains no valid body.

Is there a step I am missing between importing the part and using it.

Re: Imported shell model analysis

JDMather — Mon, 12 Jan 2015 21:45:40 GMT

Convert it to a solid body - can you attach the file here?

Re: Imported shell model analysis

Anonymous — Mon, 12 Jan 2015 22:24:36 GMT

Are you implying that shell element import does not work? Otherwise why waist time converting to a solid, if I need a shell model.

PS: The model is not a shell of a solid, it is a model of a plate construction, more specifically a section of a vessel.

Re: Imported shell model analysis

salariua — Tue, 13 Jan 2015 08:04:24 GMT

I am a bit confused on your post.

If it came in a surface body you need to convert it as solid.

Even if you need to simplify the model into a shell for FEA you need to do it in Inventor nevironment but it still needs a solid to process into thin bodies.

Re: Imported shell model analysis

Anonymous — Tue, 13 Jan 2015 09:14:33 GMT

Ok,

So, I cannot import a shell model. I need to import the model as a solid, and then use inventor to find the shells ?

I was hoping to import the model directly and then define the shell properties. The test model I am using is created with surfaces, so converting it to solids would take a lot of manual work.

Re: Imported shell model analysis

raviburla — Tue, 13 Jan 2015 15:14:54 GMT

Hi,

Inventor stress analysis always needs a solid body as a starting point for performing shell analysis. There are two commands available for converting solid to shells - (a) Mid surface command automatically converts thin solids to mid-surface shells. (b) Face offset commands provides manual control to choose the faces on solids to create shells by offsetting the faces by specified distance.

If you want to directly use surface bodies for anlaysis, Autodesk Nastran In-CAD is another addin available in Inventor. More details are available here [ http://www.autodesk.com/products/nastran-in-cad/overview ]:

Thanks,

Ravi Burla

Re: Imported shell model analysis

Anonymous — Thu, 13 Aug 2015 21:25:21 GMT

That seems very backward... I just spent an hour converting my solid bodies into surfaces so that I could do thin bodied analysis on them. Now you guys are saying that it has to start as a solid body and Inventor MUST convert it for you. What is the reason for this? This does not work in my case because Inventor does not convert it correctly, as it is a complicated part with many neusances, it can't simply be done with one button. And when it does convert it, it will not allow me to edit it in typical surface fashion.

I am basically designing a tank but would like to test the sides to see how they stand up against hydrostatic forces of the liquid inside, and the legs to see how they carry the weight. It is a completely thin bodied structure... so why can't I design it with surfaces and input for simulation? Seems so straight forward. Is this another example of Autocad trying to get you to buy more advanced software? It is getting really lame, I MISS SOLIDWORKS!!!! 😞 😞 😞 😞

Re: Imported shell model analysis

TheCADWhisperer — Thu, 13 Aug 2015 21:45:28 GMT

The design would be no different in SolidWorks than in Inventor.

Attach your SolidWorks file here (or at least your Inventor file).

Re: Imported shell model analysis

Anonymous — Fri, 14 Aug 2015 13:58:31 GMT

I have attached a shrink wrapped version of the final assembly for your reference, then I attached my simulation mockup part, which has simplified legs just to make it work better for surface meshing, and the inside faces are subdivided to allow me to simulate hydrostatic forces from a liquid known as synthesol. I am unsure of the density of synthesol, so I modelled all of my gradient pressures in terms of the top pressure assuming the density of water, so I can increase it if I find out the density is greater.

This is a very simple part, but is it worth while investing in Simulation Mechanical if this part is giving me this much trouble? I have more complicated jobs coming up, so I am getting a bit concerned... please help! Thanks!

Re: Imported shell model analysis

TheCADWhisperer — Mon, 17 Aug 2015 13:08:49 GMT

Bump.

I forgot about this one - you posted to a thread that is already marked as Solved.

The usual process is to start a new thread that includes urls to the references that you have found through search.

From quick first examination - it looks like you are doing way too much work. Back in a while with a second look and possible solution.

Re: Imported shell model analysis

Anonymous — Mon, 17 Aug 2015 21:17:01 GMT

I believe I found the solution to this problem. The first mistake was how I modelled it. The correct way would have been to use the SPLIT FACE command with work planes set to the heights i needed. After that, I applied the pressures as I had been, cranked my mesh up and just modelled as a solid instead of using thin body. It seems to have worked,

Re: Imported shell model analysis

TheCADWhisperer — Tue, 18 Aug 2015 00:05:27 GMT

When I get a chance - I will record a even easier technique. Stay tuned.

Re: Imported shell model analysis

TheCADWhisperer — Wed, 19 Aug 2015 00:26:14 GMT

@Anonymous wrote:

... The correct way would have been to use the SPLIT FACE command with work planes set to the heights i needed.....

Check how I did a single Split Face and then Thin Wall Bodies.

Re: Imported shell model analysis

salariua — Wed, 19 Aug 2015 07:22:58 GMT

That is a nice video.... loved the spiral split !

I was just about to say that you don't need to spin the model. Once a face is selected when you click in the same place you will get the next one available. (you do mention that towards the end).

That's how I measure thickness and it messes people up because they don't understand how did I do it so quickly without rotating the part.

Sorry for the detour....

Can we get some Kudos to his screencast video guys?..., that was really nice