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thermal stress

Posted 02.08.2012, 07:51 GMT-4 Structural Mechanics Version 4.1 2 Replies

Pavan Kumar Penumakala
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Hello i am solving a thermal stress problem

with a viscoplastic materail model


i defined all the bc s

but i am getting the error for viscoplastic variables as

Undefined value found.
- Detail: Undefined value found in the stiffness matrix.
There are 1217 equations giving NaN/Inf in the matrix rows for the variable mod1.ex_v
at coordinates: (0,0), (0,0.02), (0,0.04), (0.0129312,0.0335295), (0.0258624,0.0270591), ...
There are 1217 equations giving NaN/Inf in the matrix rows for the variable mod1.exy_v
at coordinates: (0,0), (0,0.02), (0,0.04), (0.0129312,0.0335295), (0.0258624,0.0270591), ...
There are 1217 equations giving NaN/Inf in the matrix rows for the variable mod1.ey_v
at coordinates: (0,0), (0,0.02), (0,0.04), (0.0129312,0.0335295), (0.0258624,0.0270591), ...
There are 1217 equations giving NaN/Inf in the matrix rows for the variable mod1.ez_v
at coordinates: (0,0), (0,0.02), (0,0.04), (0.0129312,0.0335295), (0.0258624,0.0270591), ...
and similarly for the degrees of freedom, NaN/Inf in the matrix columns

i am attachinh the model..can anyone suggest on this please

Many thanks
Pavan

Attachments:

2 Replies Last Post 06.08.2012, 21:55 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 02.08.2012, 15:05 GMT-4
Hi

I cannot open your model, as I'm far away from my COMSOL WS, but typically I see those messages when I have nmissed a material data entry, when you change the state of the material (i.e. isotropic to anisotropic) then you MUST ALWAYS recheck your material data, as this will require other data entries and some might not be predefined

--
Good luck
Ivar
Hi I cannot open your model, as I'm far away from my COMSOL WS, but typically I see those messages when I have nmissed a material data entry, when you change the state of the material (i.e. isotropic to anisotropic) then you MUST ALWAYS recheck your material data, as this will require other data entries and some might not be predefined -- Good luck Ivar
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago 06.08.2012, 21:55 GMT-4
The problem is in the square root operation in Variable eeq. Some of its derivatives are undefined when all strain components are zero. You should add a small value (such as 1e-12) under the square root.

Nagi Elabbasi
Veryst Engineering
The problem is in the square root operation in Variable eeq. Some of its derivatives are undefined when all strain components are zero. You should add a small value (such as 1e-12) under the square root. Nagi Elabbasi Veryst Engineering

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