# Discussion Forum

## New to COMSOL. Help with structural analysis.

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RSS feed   |   Turn on email notifications   |   4 Replies   Last post: January 8, 2013 5:59am UTC

David Fyda

January 5, 2013 3:04am UTC

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.

Ivar Kjelberg

January 5, 2013 10:21am UTC in response to David Fyda

Re: New to COMSOL. Help with structural analysis.

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

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Good luck
Ivar

Nagi Elabbasi
Certified Consultant
Veryst Engineering

January 7, 2013 2:08pm UTC in response to Ivar Kjelberg

Re: New to COMSOL. Help with structural analysis.

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

David Fyda

January 7, 2013 8:34pm UTC in response to Nagi Elabbasi

Re: New to COMSOL. Help with structural analysis.

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.

Ivar Kjelberg

January 8, 2013 5:59am UTC in response to David Fyda

Re: New to COMSOL. Help with structural analysis.

Hi

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

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Good luck
Ivar

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