Hi druckgott.

There are two ways to address this problem.

1. There are two circles and you have mentioned that it is one part. So you can merge the two edges and have only one edge. So when you mesh the outer surface first, the mesher puts nodes on the circle and forms elements. Then you mesh the inner circle and the mesher will use the existing nodes as the "Seed" and complete the meshing. Probably you will have to work on the element quality.

or

2. You can simply connect the nodes on the inner circle to the nodes on the outer circle using rigid bars.


I would personally recommend the First method.


Good Luck.