Issues with contact in CCX

acorella

Hi, everyone.

I'm trying to figure out how contact in CCX works and am bumping into some issues I was hoping you could help me with.

Please see attached model. The intent is to see the bearing pressure a footing puts on the ground, while preventing any tension between the parts from forming. If tension was allowed, the deflected shape is not correct. So I first have built a very simplified model.

The top layer is the footing. I applied very some soft springs to it to restrain it. The bottom layer is the ground. This is just a fixed disk.

The model does not appear to converge. What am I doing wrong?

Thanks,

Victor

Hello acorella

The reason it isn't solving is that the master and slave faces for contact are the edges instead of the surfaces so they don't meet each other.

Other issues are:

Contact stiffness per unit area is too low compared to the stiffness of the parts. This allows the footing to tilt, causing the pressure load to change direction and push it off sideways. It I increased it by a factor of 1 000 000.

There is a large initial penetration between the two parts. The contact will push them apart till their surfaces meet. That shouldn't really be a problem but might make the solution look strange with displacement in the opposite direction to the load.

You might consider constraining the ground at its lower surface instead of the edge so it compresses instead of bending.

I added contact stress to the solution that may (I'm not sure) give a better bearing pressure than stress YY.

Changed quad4 to quad8 for improved contact pressure distribution.

acorella

Thanks, Victor. That solves it!

acorella

Thanks, Victor. That solves it!