Monday, November 10, 2008

Difference in Results Between Various Versions and OSs

Julian Hallai asks...
I have been running jobs in different machines with different OS and different abaqus versions. The same input file gives reasonably different outputs. The machines were:
1) IBM Unix Machine with abaqus 6.3
2) Linux Machine with abaqus 6.7
3) Windows Machine with abaqus 6.7
So I got different results with the same version of abaqus in two different machines (with different OS) and also different results with different versions in Unix/Linux.

This doesn't happen to all input files. It has happened to about 50% of the cases (total 20 jobs).

I should also write that the material's engineering stress-strain curve has one part that's softening.

Any thoughts on that?

Thank you so much

Answer :
From Version 6.3 to 6.7 Abaqus has changed a lot, especially in the contact formulation. Please check if the input files, which exhibit remarkable difference between versions, have some specific contact definitions. These contact definitions often exhibit such differences between the versions. Material model implementation is another area where discrepancies may occur. But it is very difficult to ascertain that without looking into the exact case.

Non-Convergence of the input file between versions is very common and people at Abaqus themselves accept this and suggest to read the documentation before using any keyword. The release notes in documentation for every version are a good source of reference to check what all had been changed in the new version.

Difference in results from one OS to another for the same version is defintely a bug. You should contact abaqus support to notify the bug.


Unknown said...

How is this possible? How can you get different results with the same versions of abaqus in two different machines?

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