boundary conditions axisymmetric tube
boundary conditions axisymmetric tube
(OP)
Hey guys,
I have a question which is pretty basic, just started on a company and I am right now doing analysis on a aluminium tube which has pressure on a section inside. I of course want to approximate this as follows:
------------------------------------
^^^^^^^^
pppppppppp
My question is the boundary conditions, since I cannot lock the ends (we are interested in the movement there as well). What is your opinion.
Also, what element do you think I should use?
Regards
Mårten
I have a question which is pretty basic, just started on a company and I am right now doing analysis on a aluminium tube which has pressure on a section inside. I of course want to approximate this as follows:
------------------------------------
^^^^^^^^
pppppppppp
My question is the boundary conditions, since I cannot lock the ends (we are interested in the movement there as well). What is your opinion.
Also, what element do you think I should use?
Regards
Mårten





RE: boundary conditions axisymmetric tube
I want to make certain I understand your situation. You have a tube and you have only modeled 1/4 of its cross-section, but you have modeled its length? You want to place proper boundary conditions on it, but the end needs to be able to freely extend?
If this is the case, then place the symmetric boundary conditions on each "cut" edge, and place an axial boundary condition in the center of the pipe. Basically, if you have a cylinder, model 1/8 of the cylinder by slicing it with each of the three coordinate axes. At eac of the slice planes, place the appropriate boundary conditions.
You may also want to search these threads for a paper by JohnHors that address minimal constraints.
RE: boundary conditions axisymmetric tube
one end (either one) needs to be constrained longitudinally. i'd assume no end moment restraint.
the longitudinal sides end to react tangental load. these could have moment restraint if you think it's relevant (probably isn't).
a problem i think you'll have with modelling a axi-symmetric piece of the pipe is that the displacements probably won't work out right. i think you'll have better luck with a complete pipe ... i'd try both to see !
think too about the endload due to pressure. maybe your pipe is free to expand/contract so the poisson effects won't create load.
RE: boundary conditions axisymmetric tube
RE: boundary conditions axisymmetric tube
corus
RE: boundary conditions axisymmetric tube
Just a silly concern. If this is axisymmetric problem, why not just use an axisymmetric element with 2 DOFs. Is it necassary to to model a fourth or an eighth model using shell elements? Or is there something I am not catching here?
This should be a pure 2D problem. Cheers!
Yugabalan K