Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

New to COMSOL. Help with structural analysis.

Hey guys, I have a 2'' hollow tube that is fixed at one end and has a point load at the other end. (think cantilever)

What I need is this:

I need the radius of curvature to be 3'', so I need to know what force to apply to the end of the tube. How would I go about doing this? Please note that currently I am using a 2'' piece of tube, but the length may vary. Not sure if it matters or not.

Any help is appreciated thanks.

4 Replies Last Post Jan 8, 2013, 12:59 AM EST
Posted: 5 years ago Jan 5, 2013, 5:21 AM EST
Hi

If you have a tube, it's not only the diameter but also wall thicknes that should be considered, in addition to the length and the aterial parameters.

If you apply a "point" load you will get singularties, apply rather a Boundry load (surface for 3D, line for 2D but a tube is difficult to represent in 2D ;) or a Point in 1D.

Then if you want a radius of curvature you should rather apply a moment at the end and not a force, a force does not really give a regular radius of curvature.

Finally you need to define the "radius of curvature" there are some interesting threads on the FOURM try a search, somewhere one of the COMSOL employees have give a model to extract the radius of curvature for small and (?) lage deformations.

Once yo have the Radius you can define the moment (or force) as a global variable driven by the expression
(Calculated_Radius - Desire_Rradius)^2

--
Good luck
Ivar
Hi If you have a tube, it's not only the diameter but also wall thicknes that should be considered, in addition to the length and the aterial parameters. If you apply a "point" load you will get singularties, apply rather a Boundry load (surface for 3D, line for 2D but a tube is difficult to represent in 2D ;) or a Point in 1D. Then if you want a radius of curvature you should rather apply a moment at the end and not a force, a force does not really give a regular radius of curvature. Finally you need to define the "radius of curvature" there are some interesting threads on the FOURM try a search, somewhere one of the COMSOL employees have give a model to extract the radius of curvature for small and (?) lage deformations. Once yo have the Radius you can define the moment (or force) as a global variable driven by the expression (Calculated_Radius - Desire_Rradius)^2 -- Good luck Ivar

Nagi Elabbasi Certified Consultant
Posted: 5 years ago Jan 7, 2013, 9:08 AM EST
Hi David,

I suggest you apply a moment not a point force as Ivar suggested. As an initial estimate based on beam theory the radius of curvature due to an applied moment = E*I/M.

Nagi Elabbasi
Veryst Engineering
Hi David, I suggest you apply a moment not a point force as Ivar suggested. As an initial estimate based on beam theory the radius of curvature due to an applied moment = E*I/M. Nagi Elabbasi Veryst Engineering

Posted: 5 years ago Jan 7, 2013, 3:34 PM EST
I think I managed it, but I do have a question.

In my pipe, after running the analysis, and graphing the Von Mises stresses on the entire pipe, is there anyway to cut half the pipe off so I can see the stresses on the inside of the pipe?

Thanks.
I think I managed it, but I do have a question. In my pipe, after running the analysis, and graphing the Von Mises stresses on the entire pipe, is there anyway to cut half the pipe off so I can see the stresses on the inside of the pipe? Thanks.

Posted: 5 years ago Jan 8, 2013, 12:59 AM EST
Hi

Check the Results - Data set - Right-click - cut plane nodes and related help/doc

--
Good luck
Ivar
Hi Check the Results - Data set - Right-click - cut plane nodes and related help/doc -- Good luck Ivar

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.