failure modes and static/dynamic solver

[isok89]

Hi,


I am working on a three point bending test with a contact plate for thin walled beams.
Overall there is a symmetrical failure mode, for some beams there is an assymetrical failure mode.

For the assymetrical, yielding of the beam occurs at one side of the contact plate which leads to convergence issues if using the static solver as it is very sudden (dynamic). However when I use
the implicit dynamic solver, I get the symmetrical failure mode. Ultimate load of the experiment was 1614 N and my numerical analysis gives me 1615 N but the wrong failure mode.

so in short: experiments in lab show assymetrical failure mode, static solver shows clear assymetrical yielding prior to ultimate load and crashes as it can't handle dynamic effects. implicit dynamic solver convergences and has a symmetrical failure mode.

I do know that a colleague used the explicit dynamic solver and was able to simulate the assymetrical failure mode, but why can't that be the case with an implicit dynamic solver?

 

[cooken]

What numerical damping parameters have you used for the implicit solver?

 

[isok89]

No damping at all. What I did was to apply a 0.5% reduced thickness on one side
as an imperfection to yield the assymetrical failure mode. I'd have to see if I can yield symmetrical failure modes despite the imperfection on other cross sections.

 

[cooken]

Err, which alpha/beta parameters did you specify then? Or did you use the application= flag on the solver card?

 

[isok89]

I used application = quasi-static (the loadbearing plate in the experiments had a displacement rate of 1 mm/min). The imperfection I used does not yield numerical assymetrical failure modes
for symmetrical failure modes found in the experiments, while it does yield numerical assymetrical
failure modes, identical to the assymetrical failure modes found in the experiments. So I'm satisfied with that.

On a side note: would you happen to know how I can monitor the job from the command prompt?
Right now I use the command: abq6141 cae noGUI = "scriptname.py"
Everything works and I get an ODB file. But I don't see the process live, as in increment size, time, iterations etc.
only the cursor thicking after 'running standard'