I'm using ABAQUS/DFLUX/fortran to simulate a welding process, i can finish the simulation on a plate, perfectly controlling the flux route, but when i use the same welding method on a beam, problems found.
ABAQUS errors: Temperature at 1 nodes has fallen below absolute zero.
From the results, i can see that the temperature around the welding point is decresing, sometimes becomes negative, even down to -273 degrees.
Materials and Interaction are showed,
Thanks A LOT!
Dear Edo,
Good afternoon!
Definitely, the temperature can not go lower than the soaking/room temperature, although the cooling rate trends to be high in huge structures like this...
Maybe you should try to more robustly surround all the variables involved.
Every time that I have similar issues, I look after the answers in the fantastic book written by Dr. Øystein Grong :
" Metallurgical Modelling of Welding (Materials Modelling Series) 2nd Edition".
ISBN-13: 978-1861250360
ISBN-10: 1861250363
Good luck!
Hi Edo,
is there any chance that you are using the absolute zero temperature and Stefan-Boltzmann constant in your 'model attribute' definition? If the answer is 'yes' then that can cause problems especially if the units are dimensionally inconsistent. Please check for dimensional consistency of your thermophysical properties.
Is there any chance that your simulation job can run without your DFLUX subroutine? Perhaps, by simplifying your model to utilize a constant value heat flux input and just get the feeling that all is well. If this works fine, then by elimination, the problem could be narrowed down to the DFLUX subroutine.
If your DFLUX subroutine is 'borrowed' and not developed from scratch, it can cause you all sorts of problems. Most original authors of subroutines write snippets with the intention to quickly achieve a specific outcome, without consideration for creating a generic code. Such an outcome might be altered slightly because of your Abaqus/CAE model definition. If there is any chance that you can test tiny bits of the overall DFLUX code, without re-writing the entire program, it might unravel the cause of the unusual negative temperature outcome.
Hopefully, these suggestions are a tiny bit helpful.
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