Abaqus/Explicit contact overclosures and excessive rotations

[Konsti]

Hi,

Can anyone help me understand why is Abaqus issuing an "excessive rotation" error and aborting an analysis, when this analysis is using the explicit dynamic solver? You can find attached the error from the status file screenshot. I also attach the message file with a warning about the contact overclosures, a warning I also don't understand, although this seems to be an irrelevant thing.

The model is a building that is collapsing.

Thanks in advance,

Konstantinos

 

[FEA way]

Check these elements/nodes, their unscaled deformation at the moment when the analysis stops (and slightly before) might show you what's happening in the model. Such errors are usually caused by interactions or wrong units.

 

[Konsti]

Hi,
There is a sudden change at that moment, as two connector break and the structure is accelerating. However, I'm surprised that this is causing an error in the explicit solver, which is supposed to be working well in such sudden changes, and if fact it has most of the time in my experience.
Konsti

 

[FEA way]

And these nodes/elements indicated in the error messages belong to connectors or some neighbouring parts of the model ? Can you see any spurious deformations of the model - maybe something is deforming much more than it should ?

 

[Konsti]

I need to dig into that. It looks like actual parts are excessively deforming indeed (even breaking). Connectors are broken, so no issues there. I have no material failure, so it's weird that the elements themselves would break. Maybe the solver is going a little crazy due to contacts? The only connection I can assume given the warning messages.

 

[FEA way]

It might be a good idea to include material/connector failure in this model so that the elements will fail in a controlled manner.