Create internal crack and constrain its opening

[santiago_s]

Hi all,

I mean to create an internal crack in a Part (both 2D and 3D), with the following features:

1. I can apply internal pressure on its faces.
2. I can restrict the normal separation dn between faces. This restriction may be:
* dn=0.
* dn fixed at a value coming from a previous step.
3. The shape of the mid-surface of the crack can change upon deforming the part.
4. Contact avoids interpenetration of the faces.

So far I have no requirements on the tangential separation.

I managed to satisfy item 1 with a thin slit with parallel faces in 2D, with its 2 tips ending in a small radius. I could also do it in 3D, with a crack front ending in a "tube" with a small radius again.

But I could not find a way of constraining dn (item 2) in either case.
I suspect I need to create a zero thickness crack for this (I do not care that much about the fields about the crack tips/front), but I found no way of doing it.

How can I accomplish this task?

 

[FEA way]

I think that this may be possible with the use of equation constraint. Give it a try.