field variable not reaching its assigned value

[IceBreakerSours]

I am running a static model (with c3d20rh elements assigned with Mooney-Rivlin material definition) that is under a tensile load. A chain of connectors is embedded within the continuum elements. Nonlinear elastic connector behavior is assigned with one field variable. Nonlinear geometry flag is turned on. Once the model runs, quadratic convergence is observed. When I observe CTF.Magnitude vs. CU.Magnitude for the connectors, it is what I expect it to be. Also, this curve (CTF vs. CU) scales according to the value of the field variable.

1. However, when I display the value of the field variable for the connector nodes, it does not seem to change at all; in fact, it drops to a negative value! I feel like I am making a silly mistake in my output request or something. [In a uniaxial tensile test, I noticed the value of the field variable changes as expected.] Why does this happen?

2. Also, just to be sure, isn't Mooney-Rivlin material (provided in ABAQUS/CAE) incompressible?

3. I want to add an interaction to one of the faces of the geometry so when the top end is displaced, sliding prevents the geometry to rotate (as much as it does now) and generate contact pressure. Any suggestions would be helpful.

I have attached the INP for your comments.

Thanks in advance!

http://www.eng-tips.com/faqs.cfm?fid=376

 

[IceBreakerSours]

Perhaps I should re-phrase my major concern:

The nonlinear force-disp curve for the connector elements that the field variable is supposed to scale gets scaled as it should. However, the field variable itself does not seem to change much. How is that possible? Am I asking for the wrong output request?

Thanks.

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083