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negative stress = compressive stress ???

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Thanks for your help.

So that means that the negative stress values (blue) in the picture are compressive stress?

Or expressed in another way:

What does the minus sign of a stress value mean?

1) direction of the stress vector in the coordinate system

2) compressive stress (negative value) in difference to tensile stress (positive value)

3) both

4) other


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Christoph Mannal
June 20, 2010 9:10am UTC

negative stress = compressive stress ?


Hello,

I have a simple question. When my value of normal stress is negative, is it then a compressive stress in general. So if it is positive, is it then tensile stress?
Or does the minus and plus just mean in which direction the stress vector is pointing?

Thanks and kind regards!

C. Mannal

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Ivar KJELBERG
Moderator
June 20, 2010 5:28pm UTC in response to Christoph Mannal

Re: negative stress = compressive stress ?

Hi

what if you try something like this (its V4, check that it's the same in V3.5)

Ivar

Attachments: StressSignTst.mph
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Ivar KJELBERG
Moderator
June 20, 2010 5:31pm UTC in response to Ivar KJELBERG

Re: negative stress = compressive stress ?

Hi
And here are the view (only that in V4 it's not easy to identify which legend corresponds to which graph, but as the countour is Von Mises and von Mises >0 you should be able to identify it still unambiguously)

Have fun Comsoling
Ivar

Attachments: StressSign.JPG

5 Replies Last Post 02.12.2010, 01:19 GMT-5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 21.06.2010, 12:49 GMT-4
Hi

So how do you define compression ? w.r.t. the Comsol up or down boundary ? as for COMSOL I believe to remember, the "normal" is pointing out of the subdomain and you have negative sign then it is compression, but on the other hand in my eample I applied the force in the -Y direction (also comprssion) and I got a negative sy.

isnt this hen a question of definition ?

Ivar
Hi So how do you define compression ? w.r.t. the Comsol up or down boundary ? as for COMSOL I believe to remember, the "normal" is pointing out of the subdomain and you have negative sign then it is compression, but on the other hand in my eample I applied the force in the -Y direction (also comprssion) and I got a negative sy. isnt this hen a question of definition ? Ivar

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Posted: 1 decade ago 01.12.2010, 14:33 GMT-5
Hi,

I'm trying to find the normal stress after simulation by comsol4.0. It use to be sx_smsld in comsol 3.5a but I couldn't find it in comsol 4.0.

Could anyone help???
Hi, I'm trying to find the normal stress after simulation by comsol4.0. It use to be sx_smsld in comsol 3.5a but I couldn't find it in comsol 4.0. Could anyone help???

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 01.12.2010, 16:05 GMT-5
Hi

the Cauchy stress from the spatial frame remains sx, sy, sz, sxy... but now you need to use the prefix "solid.sx" instead of the suffix "sx_smsld" à la 3.5a

try a "CNTRL +Space" + Solid mechanics > ... in one of the plot variable fields

--
Good luck
Ivar
Hi the Cauchy stress from the spatial frame remains sx, sy, sz, sxy... but now you need to use the prefix "solid.sx" instead of the suffix "sx_smsld" à la 3.5a try a "CNTRL +Space" + Solid mechanics > ... in one of the plot variable fields -- Good luck Ivar

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Posted: 1 decade ago 01.12.2010, 17:09 GMT-5
is the ts.sx equal to normal stress at x direction?
is the ts.sx equal to normal stress at x direction?

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 02.12.2010, 01:19 GMT-5
Hi

The "ts." stands for thermal stress physics, and "sx" for Cauchy stress along x (in the Spatial frame), check the doc, it's rather well described therein (>= v4.1)

--
Good luck
Ivar
Hi The "ts." stands for thermal stress physics, and "sx" for Cauchy stress along x (in the Spatial frame), check the doc, it's rather well described therein (>= v4.1) -- Good luck Ivar

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