[petsc-users] Hints for using petscfe for plasticity -- how to update/access internal variables?

[Mark Adams]

>
>
>> That depends on the type of plasticity. For a linear hardening
> formulation it is correct that I could just apply a local operator. I’d be
> happy with that for now.
>

I would just do this for now and get it working.


> But I’d still need to save stress state and plastic strain to determine
> whether or not I’m dealing with a plasticity. I don’t know how to do that
> inside the residual evaluation. Plus DMProjectField seems to have problems
> evaluating the gradient when boundary conditions are imposed.
>

After you get the local version working try your nonlocal thing without
BCs. You may find bugs while you do this that are causing your problem, and
if not we can think more about it.


>
> Thanks,
> Max
>
>
>   Thanks,
>
>      Matt
>
>
>> I evaluate the current trial stress by adding a stress increment assuming
>> elastic behaviour. If the trial stress lies beyond the yield stress I
>> calculate the corrected stress to evaluate my residual for the
>> displacements. But now I somehow need to update my plastic strain and the
>> stress in the auxiliary fields. So in tspoststep I created another SNES to
>> now calculate the stress and plastic strain while the displacement is the
>> auxiliary field.
>>
>> I’m sure there’s an elegant solution on how to update internal variables
>> but I have not found it.
>>
>> Thanks,
>> Max
>>
>>
>>   Thanks,
>>
>>      Matt
>>
>>
>>> Thanks,
>>> Max
>>
>>
>>
>>
>> --
>> What most experimenters take for granted before they begin their
>> experiments is infinitely more interesting than any results to which their
>> experiments lead.
>> -- Norbert Wiener
>>
>> http://www.caam.rice.edu/~mk51/
>>
>>
>>
>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
> http://www.caam.rice.edu/~mk51/
>
>
>
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