Contact Pairs

[inter13]

I'm trying to use ABAQUS to model a composite slab - plain concrete resting on a trapeziodal metal deck. I'm modelling in 3D and using solid elements for the concrete and shell elements for the deck.
To model this interaction I'm using the contact pairs method, in doing so I have created a 'make contact' step before the load step to apply the boundary condition of a negative displacement on the concrete surface.
When running the analysis I am faced with the warning:

Boundary conditions are specified on inactive dof of 4221 nodes. The nodes have been identified in node set WarnNodeBCInactiveDof.

The identified nodes were the nodes at the surface of the concrete face (where I applied the -ve displacement).

The slab is supported by two pin supports and a roller which I applied to the bottom of the deck instance.

Any help would be appreciated,
Adam

 

[rstupplebeen]

Most likely the constraints that you applied included rotations which are not available for nodes of 3D elements.

Rob Stupplebeen

https://sites.google.com/site/robertkstupplebeen/

 

[inter13]

I set all the restraints to 0, only U2 = -0.01 (meters)

I also receive the warning:
Displacement increment for contact is too big.

 

[inter13]

Thanks Rob, I unchecked the rotational dofs and the warning disappeared!

I'm still having trouble completing the analysis, on last run it terminated after the increment became too small. I think I'm missing something fundamental in my interaction set-up...

 

[rstupplebeen]

I rarely use the default values for step sizes. Look at the previous run and see what size the first completed step is and set that as the initial step size. I usually set the minimum step to 1e-6 and occasionally use 1e-8. I hope this helps.

Rob Stupplebeen

https://sites.google.com/site/robertkstupplebeen/

 

[inter13]

Thanks, I changed the minimum step size on your recomendation.

I'm wondering if there a recommended magnitude or rule of thumb for the negative displacement to bring the parts in contact?

 

[rstupplebeen]

I try to have the parts initially in contact. If there is a rule of thumb it is probably mesh size dependent.

Rob Stupplebeen

https://sites.google.com/site/robertkstupplebeen/