Constraints and deformable body

[forstay]

Hi,

I'm trying to link a deformable body to a base component, but I can't find the procedure and the main idea of doing this. Do I have to start with modelling of the deformed body (its final form) or I have to create a body using existing paper drawings and only after that somehow to deform that body?
Please, check out the attachment (assembly file called ASSY.prt). Here a rounded surface of a bow ("prod") should be connected to base plate ("riser"). In reality that curvature will be vanished (obviously the bow will deform) due to the bolts. Could you show me please how should it look like. Thanks!

NX version 8.0

 

[JohnRBaker]

Look at the attached model. It took 4 constraints but it'll stay where I put it.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
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To an Engineer, the glass is twice as big as it needs to be.

 

[forstay]

Thank you. Now I'm using your suggestion in constraints. Nevertheless due to the curvature of the arm there was a gap between the arm and a base plate. Thats why I've changed the model of the arm in order to reduce that curvature. Now the problem is solved.

So in general, how should an engineer create here a deformable body - make the model with already deformed shape (like spring under loading) OR make the model in original (designed) shape?

 

[JohnRBaker]

Depends. If you're going to be manufacturing the part from the model, in it's undeformed state, then you'll need to create the model in that state. Now as to how you show it in it's deformed state in the assembly, you have basically two choices. If you're only going to need to show an assembly with the part in a single pre-defined and known state of deformation, you could create your original model with a second deformed representation and create two different Reference Sets, one to be used when creating your manufacturing Drawing and the other to be used when creating your assembly where it's shown deformed. The other approach would be to create a true 'Deformable' part and use it in the assembly set to show the desired level of deformity. In either case, you will need to build the model so that that portion of the model which is bolted in shown flat and that the deformity is confined to that portion of the model which would actually deform when put under stress.

I'll work-up some examples and get back to you.

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.

 

[JohnRBaker]

OK, attached are two new files, a new assy and a new model for your 'Bow' halves.

Note that the approach I used to model the Bow halves will give you the proper length, both in the flat and the deformed state. Also you can change the amount of deformation by editing the value of the Expression 'Draw_Dist' as long as it's a positive number (it CANNOT be set to ZERO or to some negative value). Note that that I used that Reference Set approach, which I mentioned earlier. What I do was model both the flattened (as manufactured) solid and the deformed (as assembled) states. I also went ahead and created both the 'left-' and 'right-hand' parts so that actually the part model now contains 3 Reference Sets, 'MODEL' for default flattened state as well as a 'DEFORMED-LEFT' and a 'DEFORMED-RIGHT'. In the Assembly (note that I reused your 'riser' part) I show both the Left and Right bows installed. And as previously mentioned, I modeled these so that the portion of the Bow that is bolted to the frame is flat and only that portion which extends past the frame is deformed.

Anyway, I hope this helps get you in the right direction. If you would like me to look at using a true 'Defomable' Component, I think can get that to work as well but it'll take a bit more effort to get it work reliable.

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.

 

[forstay]

JohnRBaker,

Thank you for the most helpful answer I ever got! The problem is completely solved!