Expanding a straight cylinder in a curved tube

[jamescook]

Hi,
i am trying to expand and deflate a cylinder (modelled as a shell) within a deformable curved tube. I am expanding and deflating the cylinder using displacement boundary conditions and a cylindrical csys. The analysis works fine except for the balloon which returns to its initial position when deflated whereas I want it to deflate to the centre of the deformed tube. Any ideas on this problem?

 

[corus]

I can't understand how you expand the cylinder by displacements as surely you're simply applying those displacements to the curved tube on contact? Some pictures of the model might help.

ex-corus (semi-detached)

 

[rstupplebeen]

A description of your end goal would also be useful is this for a sent?

As a guess if you turn on stabilization and expand the balloon with a pressure load then you might get your desired results. I am guessing the stabilization is needed to remove rigid body motions because the balloon will be smaller than the bent tube.

I hope this helps.

Rob Stupplebeen