Constraints with limits

[PetrGrygar]

Hi!

I'm here with another question, and I would be very glad if someone has helped. Is there a way, how to define constraint with limits? For example, I'd like to define that this node can move only by 2 millimeters, no more.

Thanks for any reply.

 

[rb1957]

sounds like a contact situation ?

re-reading your question, do you want to ...

1) stop the structure deflecting after 2mm (as though the structure has contacted the ground) and then react load ? or

2) make the structure stiff enough so the point only deflects 2mm ?

1) is contact, 2) is much harder (it's a structural optimisation problem, changing the stiffness of the structure to limit displacements).

Quando Omni Flunkus Moritati

 

[PetrGrygar]

The 1) is Right. But I'm looking for a way, how to write this BC in this way: displacement <2, not displacement = 0. Is it possible? It would be most useful, for example for modeling bearings, with an acceptable angular rotation e.g. spherical roller bearing. Simply in the middle of the bearing, perpendicular to it's axis I would created a cylindrical Csys, and then wrote this condition for e.g. 2°.

 

[rb1957]

look into gap elements

Quando Omni Flunkus Moritati

 

[BlasMolero]

Hello!,
You have two options:
• CBUSH element allows to define in the PBUSH property where you can enter a curve of load vs. deflection and run a nonlinear analysis SOL106.
• CGAP elements, where you can define a GAP distance (the two mmm) and the compression stiffness when the GAP is closed. You can run linear SOL101 analysis or nonlinear SOL106 analysis.

Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

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