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horizontal / vertical stress ratio

Posted Feb 2, 2011, 5:22 a.m. EST Structural Mechanics Version 4.1 4 Replies

Juergen Hansmann
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Dear all,

when I create a simple geometry, e.g. a square or a cube in the structural mechanics mode (v.41) and apply a body load, representing gravity (i.e. the force vector Fv is 0,0,rho*g), the ratio of the horizontal to vertical stresses is then calculated by Comsol in a way, that the horizontal stresses = vertical stresses * ( nue / (1-nue)), where nue is the poissons ratio.

How can I define my own horizontal to vertical stress ratio?
e.g. I want to assume hydrostatic conditions and have a ratio of 1 but keep my poissons ratio.

Is there a way to prestress the model to achieve a defined horizontal to vertical stress ratio, that still allows to constrain all the model boundaries with "roller" boundaries and only the top surface of the cube or the top line of the square shall be "free"?

Thanks a lot for a hint,
Juergen
4 Replies Last Post Feb 3, 2011, 6:51 a.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 2, 2011, 9:37 a.m. EST
Hi

isnt it rather nu=0 (since nu should be <0.5 in any case)

to prestress, use a stationary solver with boundary or volume loading, and then stoe and restart next solver section from there

--
Good luck
Ivar
Hi isnt it rather nu=0 (since nu should be
Juergen Hansmann
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Posted: 1 decade ago Feb 3, 2011, 1:57 a.m. EST
Hi Ivar,

thanks for your reply.
A poissons ratio of 0 would not really make sense in my case.
But I managed to prescribe a horizontal/vertical stress ratio (k0) of 1 now in a bit complicated way, but it seems to work so far.

Best wishes,
Juergen
Hi Ivar, thanks for your reply. A poissons ratio of 0 would not really make sense in my case. But I managed to prescribe a horizontal/vertical stress ratio (k0) of 1 now in a bit complicated way, but it seems to work so far. Best wishes, Juergen
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 3, 2011, 6:29 a.m. EST
Hi

then work with the full tensor, its heavier but certainly correct (if you get the right values in the right positions, but that should be possible though)

--
Good luck
Ivar
Hi then work with the full tensor, its heavier but certainly correct (if you get the right values in the right positions, but that should be possible though) -- Good luck Ivar
Juergen Hansmann
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Posted: 1 decade ago Feb 3, 2011, 6:51 a.m. EST
Hi Ivar,

thats more or less exactly what i did!
I use several body loads and boundary loads and pass the stress state to the initial stresses and strains of another model and the result is, what I would like it to be and of course what I would expect to be correct.

Best regards,
Juergen
Hi Ivar, thats more or less exactly what i did! I use several body loads and boundary loads and pass the stress state to the initial stresses and strains of another model and the result is, what I would like it to be and of course what I would expect to be correct. Best regards, Juergen

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