Folded piece of fabric

[schnautza]

I'm trying to figure out if it is possible to model a folded piece of fabric that can be unfolded. Starting with the unfolded position, we have a piece of material that will be approx 7'-6" wd x 6'-4" lg. First, the 7'-6" section will be folded into 3 pieces (2'-6"). Then the result will be folded in half in the other direction, giving us a 3'-2" x 2'-6" 6-layer folded fabric. I assume that something like this can be done with lofted lines to make surfaces and then applying a thickness. I have gotten as far as the first set of folds with adequate results by lofting lines on parallel planes, but I am at a loss as to how I can now do the final fold...because these three layers all need to double back over each other. Any ideas? Also, once folded, is it possible to unfold easily? Or do I just build a fresh new model for this view?

[cwhetten]

Modeling double folds in Inventor sheet metal is not easy, especially if you want to get a meaningful flat pattern.

I experimented with this idea by modeling a sticky note that has been folded in half one way, then in half again the other way.  The first fold is trivial, but the second is not.  The particularly difficult part is the corner where both folds come together:

After several failed attempts, I was able to get it to work by creating the radii of the second fold using the contour roll tool (see attached part, version 2012).

Use the contour roll tool with caution, as it often returns meaningless flat patterns.  In this very simple case, it appears to have worked properly, but I can't say if it will for your project.

Cameron Whetten
Inventor 2014

[JDMather]

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@schnautza wrote:
.... I have gotten as far as ....

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Attach the *.ipt file of what you have completed so far.
If I follow your problem description correctly - someone posted an example here several years ago that worked.

[schnautza]

Dang it, I would attach the file, but this forum is acting up again and I once again cannot attach a file or format text. Soon as it works again, I'll post it. I did find a feature that is helping me - "bend part". I made the full length part and was able to successfully fold the entire thing in half.

[schnautza · Accepted solution]

I started a new part with the "bend" feature in mind (Modify-->Bend). Start with a full sized sheet, then just add bends as needed. You can double and triple bend as many layers as you want. Turned out to be super easy. Still can't attach the example, but there is the answer. To unfold it, all I have to do is suppress or remove the bend.

[rdyson]

Be aware that bend does not calculate the bend allowance like the sheet metal features do.
Given you're dealing with fabric, it's probably not important, just wanted to point it out.
Also, I would derive the flat piece into a new part to add the bends. That was you can document both the flat and the folded part.

[schnautza]

What do you mean by "bend allowance"? Something to do with the stretch of the material? And also what do you mean by "derive the flat piece"...just save it as another file? I plan on doing that.

[rdyson]

Yes to bend allowance.
Start a new standard.ipt, cancel out of sketch if necessary.
Go to manage>insert>derive and choose your flat part. Apply your bends.
The bent part is now linked to the flat, changes to the flat will update the bent part.