Autodesk Inventor

[#1]

Hello community,

When trying to shell a part i get the error: the attempted shell operation was unable to solve for a vertex....etc. i have attached the problem part file, of which the drawing is a fairly complicated frame (a chassis concept for a 3 wheeled race car i am designing)

How the part was made:

It was created in an assembly using the frame generator tool and then converted to part file using the shrinkwrap feature. When using the shrinkwrap command, i selected: single solid body merging out seams between planar faces, All hole patching, break link, and remove all internal voids. and then when trying to shell i get the error message when selecting a wall thickness of 2mm.

i cant understand why the shell feature does not work as i have successfully shelled a very similar part file (with only slight differences in geometry from the file attached in the same way as what i am trying to do with this part). i can provide this part file upon request or the assembly file from which either was created. i need to shell the component in this way so that i can run accurate FEA (stress analysis) for crash simulations on it

Any help would be very much appreciated, thanks

I am using inventor 2013 (64bit OS)

[#2 · Accepted solution]

Hi,

Many thanks for posting this problem! I've taken a look at your operation, and it appears that there is just some geometry on this particular model that is causing difficulties for the Shell computation (i.e. I do not believe this to be a general limitation of this workflow). I've logged the failure to shell this model as a defect with the development team (Defect ID 1460070, should you need this for future reference) so that we can try to get this case working for a future release.

I've managed to come up with a workaround for this model (IPT attached - End of Part marker is rolled-up to reduce file size): this involved omitting problematic faces from the model before shelling, then using the Thicken and Delete Face tools to hollow-out and attach these segments separately.

Here's the full process I followed:

1. To find the region(s) that are problematic for shelling, I made a sheet copy of the model, and used the Thicken tool to 'simulate' the Shell operation face-by-face. By continually adding faces to my Thicken feature, and noting where they failed, I narrowed-down the problematic regions to a few model faces.
2. Starting afresh, I made sheet copies of these problematic model faces, using the Offset surface tool with an offset value of 0.
3. I then used the Delete Face tool, with Heal enabled, to remove the problematic portions from the solid model, leaving me with just a solid shellable part and a set of separate sheets. 
4. I used a 2mm Shell to hollow-out the main solid, then performed 2mm Thicken operations on the sheets to turn these into hollow tubes of the same thickness.
5. The only remaining task was to clean-up the interfaces between the thickened tubes and the main shell. Due to the workaround used, these tubes did not hollow-through to the main shell, and the interfacing model faces did not meet up nicely, leaving some small undesirable voids. I used Delete Face with Heal to create the hollow-throughs, and to tidy-up the interfaces (careful attention was needed here, to make sure all undesirable voids were deleted).

I made this sound complicated, but hopefully you can see from the IPT that it's not that bad . The aim of giving a lengthy explanation here was to hopefully offer some tips that might be useful if you encounter a similar problem in the future.

I hope this has helped you get around this particular issue. If you encounter problems on an similar parts in the future, please don't hesitate to post them here or email them to myself (at jake.fowler @ autodesk.com), as this kind of data is very useful in helping us improve Inventor for future releases.

Many thanks!

Jake

[#3]

Hi Jake,

Many thanks, i have followed your procedure and had a go myself with successful results, so should be able to deal with the issue should the problem arise again.

Again thanks for your help

Dan