Rigid Element in NonLinear

[Anonymous]

Can you advise how it is recommended to model Rigid Elements in non-linear analysis, where there is no such thing, bearing in mind all considerations it goes with, to translate from slave points to master point all translations and rotations ?

[swlamech]

I am very interested in this as well

[Anonymous]

@AstroJohnPE may we kindly ask for your help? As most experienced user you certainly have valuables to add in this subject, if not please refer us to one of your collegues. Much appreciated!

[AstroJohnPE]

Just for everyone's background, a "rigid element" in a linear stress analysis is able to transfer loads in directions selected by the user.  So if you wanted to transfer forces in only X and Z and a moment about Y, you can setup the element to do that. With a large stiffness assigned to the element, it can act as if all of the nodes at the ends of the rigid element deflect the same amount. (I assume that's where the term "rigid" comes from. 🙂

Nonlinear analysis does not have anything with this flexibility. The closest substitute would be beam elements with end releases applied so that forces or moments are not applied in certain directions. You probably need to be somewhat careful -- or at least be aware -- of whether the beam elements part is stable, what happens with the beam orientations and the end releases if the beams go through a large displacement, etc.

Also, if you make the cross-section of the beam elements "large" to simulate a rigid link, you may want to make the mass density small so that the inertia of the "fake" beams does not affect the analysis.