Sketch Pattern vs Solid Pattern

[ChaseWichert]

NX 8.5.2.3

I am trying to figure out the best way to model a complex sketch that can either be modeled solely in the sketch, IE creating part of the sketch and patterning it 112 times creating a complex sketch, and I get a warning that it could cause the sketch to solve slowly, or create that one instance, revolve it as a solid, then instance it 112 times then join them all as one body. The key thing is that I need to change the overall length of the finished body, think accordion. So I want it to update as fast as possible. What would be the best way to model an accordion?

Thanks,
Chase

NX 8.5.1.3

 

[JohnRBaker]

It would help if you provided at least a picture of what you're trying to model.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[ChaseWichert]

Here you go.

NX 8.5.1.3

 

[JohnRBaker]

So you're saying that the number of 'pleats' in the bellow is constant just that the 'period' will change as the length is increased or decreased, correct? Is it posible the profile of this bellows could be represented as a 'Sine Curve'? Is so, have you considered using a law curve instead?

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[ChaseWichert]

Hmm... I've never worked with Law Curves.. Not sure how to use them.

NX 8.5.1.3

 

[JohnRBaker]

As an example of what I mean, take a look at the attached file (you'll have to unzip it first). In this file you'll find a 'Sine Curve' with 112 pleats revolved to form a 'bellows'. You'll see the Expressions that control the 'Height' of a pleat, the 'Nmber of Pleats' and the over all 'Length' of the bellows. You should be able to figure it our from here.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[ChaseWichert]

That doesn't quite work in this case, this is what it looks like when they are compressed.

NX 8.5.1.3

 

[JohnRBaker]

Could you send a picture showing the dimensions of a couple of pleats when fully expanded?

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[ChaseWichert]

I think this should have everything you need. And there is only 26 bellows in this one I think.


NX 8.5.1.3

 

[JohnRBaker]

OK, here's another shot at this using only 3 sketches and then Patterning one of the sketches to create the bellows. I know that we really need a final sketch to finish off the other end but I'll leave that to you. Also note that I didn't use you exact dimensions but they're close, however you can change the length of the bellows by editing the Expression 'Pitch'. It's currently set to 0.284in but to see an almost fully compressed bellows set it to 0.130in. Again, I'll leave it to you to hook it up to your 'PrecentExpanded' expression.

So take a look and let me know what you think.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[ChaseWichert]

I did a time comparison with one that had the patterning done in the sketch and the one where the patterning was done outside of the sketch, and on my machine the one you provided took 12.3 seconds, the one that I had took 5.4 seconds. If I did every operation that I needed, expand and contract two sets of bellows at the same time, join all of the bodies together, then trim a cylinder using the joined bodies (to get an oil filled bellow) and then take a 1/4 cut out of everything for sectioning purposes it takes 14.4 seconds. The previous way I had done it was to link all of the bodies in to an assembly take the intersection curves of the bellows component, and revolve the sketches, this took anywhere from 4-5 minutes to update. There is a large difference when you have something assembled "correctly" IE like the BOM shows and when you modify your model designed for graphics. I am going through and remodeling and changing the assembly structure to avoid an unnecessary updating and what not. I think we have a pretty good set up now. My boss wants a slider where you can dynamically expand and contract the bellows, but I have a feeling that NX isn't designed for complex dynamic animations. Just the rendering animations. Which I understand.

Thanks for the help!

NX 8.5.1.3