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2D surface plot of positive normal stress

Posted Dec 7, 2011, 4:52 a.m. EST Results & Visualization Version 3.5a 6 Replies

Birgit Palm
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Dear community,

I have an old model in V3.5a (quite big) where I need a special plot for a presentation. I calculated (2D axisymmetric) temperature and stresses and show normal radial stress, which is in a range between 69 and -200 MPa. As I want to have a closer look at the positive stresses, I tried to surface plot the expression "sr_maxi>0[MPa]". Unfortunately the surface plot is now dimensionless and shows a color range between 0 and 1. I need to illustrate the positive stresses as calculated, in MPa - how can I do that? Does anyone have an idea?

Thanks for your help,
Birgit
6 Replies Last Post Dec 12, 2011, 4:08 p.m. EST
Edgar Kaiser
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Posted: 1 decade ago Dec 7, 2011, 9:35 a.m. EST
Birgit,

I think your expression must be sr_maxi*(sr_maxi>0)

This will plot all values > 0 and will plot 0 for negative values.

Maybe just defining a range for the plot would yield the same result?

Cheers
Edgar
Birgit, I think your expression must be sr_maxi*(sr_maxi>0) This will plot all values > 0 and will plot 0 for negative values. Maybe just defining a range for the plot would yield the same result? Cheers Edgar
Birgit Palm
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Posted: 1 decade ago Dec 8, 2011, 2:37 a.m. EST
Dear Edgar,

thanks for your reply.
Using the expression the square stresses [Pa^2] was shown, not what I wanted. But as usual, the simple things work best - just adjusting the range to 0-70 MPa gave me the needed picture. Thanks for the hint - I sometimes tend to think too complicated ;-)

Greetings, Birgit
Dear Edgar, thanks for your reply. Using the expression the square stresses [Pa^2] was shown, not what I wanted. But as usual, the simple things work best - just adjusting the range to 0-70 MPa gave me the needed picture. Thanks for the hint - I sometimes tend to think too complicated ;-) Greetings, Birgit
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Dec 9, 2011, 1:08 a.m. EST
Hi

What about trying sr_maxi*(sr_maxi[1/Pa]>0) that should remove the extra Pa unit, and Boolean's work best dimension-less

--
Good luck
Ivar
Hi What about trying sr_maxi*(sr_maxi[1/Pa]>0) that should remove the extra Pa unit, and Boolean's work best dimension-less -- Good luck Ivar
Birgit Palm
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Posted: 1 decade ago Dec 12, 2011, 10:41 a.m. EST
Dear Ivar,

thanks also for your reply - I just tried your option and it worked - the stress is shown in MPa. Although the edition of the range has the advantage that everything below 0 is left blank and only stresses above 0 MPa is colored, whereas your suggestion already displays 0 MPa in dark blue. The option with everything blank besides >0 MPa is a bit clearer for looking at the overview.

Best regards,
Birgit
Dear Ivar, thanks also for your reply - I just tried your option and it worked - the stress is shown in MPa. Although the edition of the range has the advantage that everything below 0 is left blank and only stresses above 0 MPa is colored, whereas your suggestion already displays 0 MPa in dark blue. The option with everything blank besides >0 MPa is a bit clearer for looking at the overview. Best regards, Birgit
Edgar Kaiser
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Posted: 1 decade ago Dec 12, 2011, 10:47 a.m. EST
Hi Ivar,

I find it a little funny (or isn't it strange?) that a boolean expression returns a unit? I am wondering if this is consistent from mathematical point of view.

Cheers
Edgar
Hi Ivar, I find it a little funny (or isn't it strange?) that a boolean expression returns a unit? I am wondering if this is consistent from mathematical point of view. Cheers Edgar
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Dec 12, 2011, 4:08 p.m. EST
Hi Edgar

I do agree with you, but that is the only explanation I can come to if there is a ^2 on the units, or there are something more on the line not shown. I havent rechecked, I mostly make my variables without units to enter a boolean expression, but in some fields its not possible, it flags an error, it seemsthat units are not accepted systematically and everywhere. Anyhoe I do not have 3.5 running anymore so I cannot check either ;)

--
Good luck
Ivar
Hi Edgar I do agree with you, but that is the only explanation I can come to if there is a ^2 on the units, or there are something more on the line not shown. I havent rechecked, I mostly make my variables without units to enter a boolean expression, but in some fields its not possible, it flags an error, it seemsthat units are not accepted systematically and everywhere. Anyhoe I do not have 3.5 running anymore so I cannot check either ;) -- Good luck Ivar

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