Initial conditions of an UMAT Subroutine

[vazaar]

Hi all,

I wrote an UMAT-subroutine which changes the Youngs modulus based on the strains. It seems to work, except that the initial conditions of the state variables are not read by Abaqus. I defined the intial state variables in an SDVINI subroutine, and put this in the same file as the UMAT subroutine (at the top).

For my material definition in the input file I have the following (to tell abaqus that I user-defined the initial variables for the states in the SVDINI subroutin)

Material, name=USERMAT_ELASTIC
Depvar
68,
User Material, constants=1
0.3
INITIAL CONDITIONS, TYPE=SOLUTION,USER


In the documentation I found it should be done like this if you use a SDVINI subroutine.
However, when abaqus reads the input file, it gives the following warning

WARNING The following keywordsparameters are not yet supported by the input file reader
---------------------------------------------------------------------------------
INITIALCONDITIONS, TYPE=SOLUTION.


It is weird that USER (after solution) is not present in the warning. The job runs without errors , but the initial conditions for the state variables are not recognized, and instead a value of zero is used.

Does anyone know what I do wrong here? It would help a lot.

Also, I was wondering if anyone knows how UMAT applies material properties. In my definition I make the Youngs modulus dependent on the strain. Does UMAT take every strain at every node and apply different properties at every node? Or it it even for every integration point? Or maybe it takes the average strain for the whole model and applies one Elastic modulus to the whole model? Im curious about this but cant find this in the documentation.

Thanks in advance and kind regards

 

[vazaar]

Hi all,

The problem is solved, so I thought I write a solution here if anyone else in running into these problems.

Apparently some keywords are not recognized by Abaqus CAE from the input file, even if the expression might be correct. I downloaded an example input file for an SDVINI subroutine and even then some keywords were not recognized (I made sure the versions of Abaqus were the same). It might have to do with the fact that input files existed before Abaqus CAE and were not originally meant to be imported this way. Anyway, to solve this, you can rightclick on your model, then click edit keywords. Paste your line in here, make sure it is on the right locations, then it shoud work.

Greetings