Hi Mason,

I have not seen any use of NLGEOM in which it has been applied only to part of a model. The manual (KEYWORDS/Step) says "Once the NLGEOM option has been switched on, it will be active during all subsequent steps in the analysis". This is a step command, so I assume it invokes NLGEOM for all parts of the model that are active in the step.

Can you explain why you say that the "cohesive pore pressure element in Abaqus... requires Nlgeom switch turned on"?

Regards,

Simon

Hi Simon,

Thanks for your answering. When using cohesive pore pressure element, the thickness of the element needs to be updated. This is important and also required by Abaqus. If you turn Nlgeom off, the software will give you a warning that you should turn the switch on. If you ignore the warning, you would get some results which are strange.

I am wondering whether I can keep Nlgeom off and try some methods to update geometry of the cohesive element only.

Best,

Mason

Hi Mason,

Are you using the following option:

*COHESIVE SECTION, RESPONSE=TRACTION SEPARATION,

THICKNESS=GEOMETRY

Also, what is the reason that you are unable to run a fully NGLEOM model?

Regards,

Simon

Hi Simon,

Yes, I am using COHAX4P type element.

Except cohesive pore pressure element, the rest model needs to be calcualted based on their initial geometry. Within the rest model, there are several contacts. If Nlgeom is on, the contacts need to be finite sliding, which leads a weird result.

Ideally, the model should be calculated with Nlgeom off and small sliding contact if ignoring cohesive pore pressure element.

Best,

Mason