Problems with Abaqus 6.3

[Crisalvim73]

Hi,
I was working with Abaqus 6.1 to model a plane axissymetric visco-hyperelastic membrane subjected to an internal pressure. It was OK, but when I changed to the new version of Abaqus(6.3), I have problems with overconstrains in many internal nodes. We are working in an Academic licence, so we have not the right to a full support. Could any one give an idea to solve this problem? Have this problem happened with anyone?
Thanks, Cristina

 

[corus]

Over constrained nodes tends to apply to contact conditions or tied nodes in which you have restrained them and tied them to another set of nodes. I'm not sure why 6.1 would have worked and 6.3 doesn't. The nodes which are over constrained will be identified in a set that Abaqus creates which you can see in Viewer. This might help in identifying if you have applied restraints to that set.

 

[Crisalvim73]

Hi again,
Thank you very much for you help, but I think I didn't explain my problem well.
My model is very simple: a plane rubber disc subjected to a pressure, pinned in it edges. I'm not using contact elements and tied nodes. I use a sweep discretization, with 3 and 4-nodes membrane elements.
The model works well when I use the hyperelastic properties (Ogden funtion) only , but when I include viscoelastic properties all internal nodes get overconstrainted, neither in the *static step, nor the *visco. How can I understand it????
Thanks, Cristina

 

[Crisalvim73]

Abaqus 6.3 has a bug with viscoelastic behaviour...