Constrain general position of cylinder using springs or connectors

[jamescook]

Hi, I am expanding an open ended cylinder (shell) with pressure loading inside a deformable curved tube (solid). I want to constrain the cylinder so that its centre line (at the midpoint of the cylinder) will coincide with the centre line of the curved tube throughout the analysis. I think this can be done by using either spring elements or connectors but so far my attempts have been unsuccessful.