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Hoop stress, radial stress

Posted Jan 11, 2016, 6:20 a.m. EST Version 4.4 6 Replies

Djones David
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Hi all,

In 2d axisymmetric , how to plot the hoop and radial stress? (there are many stress options in the insert expression tab)

Thank you
6 Replies Last Post Mar 2, 2016, 1:29 a.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 9 years ago Jan 12, 2016, 3:05 a.m. EST
Hi

have you checked ?
www.comsol.eu/community/forums/general/thread/34639

--
Good luck
Ivar
Hi have you checked ? https://www.comsol.eu/community/forums/general/thread/34639 -- Good luck Ivar
Henrik Sönnerlind COMSOL Employee

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Posted: 9 years ago Jan 12, 2016, 3:42 a.m. EST
Well, in 2D axisymmetry it is easier than in the thread pointed to by Ivar :-)

The hoop stress is solid.sphiphi.

If you by 'radial stress' mean the direct stress in the R direction, it is solid.srr.

Regards,
Henrik
Well, in 2D axisymmetry it is easier than in the thread pointed to by Ivar :-) The hoop stress is solid.sphiphi. If you by 'radial stress' mean the direct stress in the R direction, it is solid.srr. Regards, Henrik
Djones David
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Posted: 9 years ago Jan 14, 2016, 4:42 a.m. EST
Thank you Ivar and Henrik for your replies.

Henrik are these var available on v 4.4 because they are not recognized ?(sorry for not mentioning it)
I use stress tensor local coordinate system (as in the thread ivar mentioned) for example solid.sI11 to plot axial stress but i m suspicious about the results.. i wonder (on that) if comsol finds the parallel surface to its axial direction for an inclined geometry to calculate the axial stress..?
My geometry is inclined at a part like in the photo attached(supposing the bold line has axial direction)

Thank you Ivar and Henrik for your replies. Henrik are these var available on v 4.4 because they are not recognized ?(sorry for not mentioning it) I use stress tensor local coordinate system (as in the thread ivar mentioned) for example solid.sI11 to plot axial stress but i m suspicious about the results.. i wonder (on that) if comsol finds the parallel surface to its axial direction for an inclined geometry to calculate the axial stress..? My geometry is inclined at a part like in the photo attached(supposing the bold line has axial direction)

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Henrik Sönnerlind COMSOL Employee

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Posted: 9 years ago Jan 14, 2016, 5:45 a.m. EST
Hi,

Local stress components have directions which you define yourself, by assigning a local coordinate system to the material. So when using the solid.sI* variables, you have full control over the orientation.

Regards,
Henrik
Hi, Local stress components have directions which you define yourself, by assigning a local coordinate system to the material. So when using the solid.sI* variables, you have full control over the orientation. Regards, Henrik
Nicolas Degrenne
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Posted: 9 years ago Feb 29, 2016, 8:58 a.m. EST
I share a similar problem, but with version 5.2.
I consider a disk of radius R=10mm and height of Z=1mm, generated with a 2D axisymmetry. I impose a displacement (strain) of the radius of 3.8466E-3mm and I measure the stress on the volume. The file is attached.
The stress indicated by COMSOL for solid.mises, solid.sr, and solid.sphi is 4.0191E7. My analytic calculation would rather indicate a value of 2.6315E+07 for the radial and for the tangent stress.

Here are my questions:
1)How does the Von Mises stress combines the radial and tangent stress components?
2)How to measure only the radial stress value?

Regards,
Nicolas
I share a similar problem, but with version 5.2. I consider a disk of radius R=10mm and height of Z=1mm, generated with a 2D axisymmetry. I impose a displacement (strain) of the radius of 3.8466E-3mm and I measure the stress on the volume. The file is attached. The stress indicated by COMSOL for solid.mises, solid.sr, and solid.sphi is 4.0191E7. My analytic calculation would rather indicate a value of 2.6315E+07 for the radial and for the tangent stress. Here are my questions: 1)How does the Von Mises stress combines the radial and tangent stress components? 2)How to measure only the radial stress value? Regards, Nicolas
Henrik Sönnerlind COMSOL Employee

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Posted: 9 years ago Mar 2, 2016, 1:29 a.m. EST
Hi Nicolas,

For the definition of von Mises effective stress, please se the documentation or en.m.wikipedia.org/wiki/Von_Mises_yield_criterion . With two normal stress components equal and all other stress components zero, it follows that the von Mises stress will get the same value.

The radial stress component is solid.sr as you expected.

You have to revisit the analytical calculation. Note that the stress state is biaxial and the strain state is triaxial in your example.

Regards,
Henrik
Hi Nicolas, For the definition of von Mises effective stress, please se the documentation or https://en.m.wikipedia.org/wiki/Von_Mises_yield_criterion . With two normal stress components equal and all other stress components zero, it follows that the von Mises stress will get the same value. The radial stress component is solid.sr as you expected. You have to revisit the analytical calculation. Note that the stress state is biaxial and the strain state is triaxial in your example. Regards, Henrik

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