Penetration in contact

[isok89]

Hi,


I'm modelling a three point bending test by applying a loadbearing plate (contact). I'm satisfied about my results.
However I notice there is penetration of the rigid plate by the slave surface at the corners. Will this affect my results and if so how I can prevent penetration? Currently I'm using the penalty method, I about using the direct method.

 

[Mustaine3]

First you should refine the mesh. Afterwards you might scale the penalty stiffness or switch to direct method.

 

[IceBreakerSours]

If the amount of penetration is a tiny fraction (<5%) of the characteristic element length, then odds are you are going to fine by simply ignoring it.

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[isok89]

I solved it by setting both surfaces as master and slave, with some improvement in results.

However, some of my models diverge at time step 0.99, which is very odd.
After ultimate load at 0.40, the maximum increment step is continuosly
used (0.05), until 0.99, eventually the increment gets too small and Abaqus aborts. Does anyone know the reason of this?


I don't mind this but when running from
COMMAND PROMPT, this will lead to a crash of my loop within my script.

 

[Mustaine3]

When steps abort at 0.999 step time, it usually indicates that contact stabilization is used and the contact situation is not stable when this stabilization is removed at the end of the step.

 

[isok89]

I used the implicit dynamic solver without any stabilization.
The job doesn't abort with an extremely fine mesh (5 hours simulation instead of the usual 1 hour)

I use a loop in my script to simulate all my models.
one loop goes as follows:

1. create model
2. submit job
3. use command .waitforcompletion()
4. export xydata
1. create model...etc

If my job aborts, the complete loop crashes because the 3rd command is no longer valid.
Is there some kind of IF statement I can implement in case the job aborts?

I also thought about creating a while loop after submitting the job and continueosly reporting
the step time to a txt file, through which my script is looking for the maximum step time value.
if it's higher than 0.99, the the job should be terminated and all xydata should be reported.

 

[DrBwts]

In Python you can use the "try, except" construct.

https://docs.python.org/2/tutorial/errors.html

Basically it tries a command, in your case " command .waitforcompletion()" and if it returns an error it will catch it and deal with it however you want. You can then continue with your code without it crashing.

The above link is for Python 2.7 but it should work for any 2.x but check first.