[steveivy]

Hi
A lot of information but I think it is straightforward. Thank you in advance!

Some background information:
I am modeling an aircraft wing. And I have surface body represents the wing skin and solid bodies for ribs. In the CAD model, the surface body is lofted based on the ribs profile, so the surface should be right on top of the rib. So in the ANSYS Mechanical, I set a thickness of 2mm for the surface(skin) and the offset is bottom. For contacts, it is set to Bonded.

Here are the questions:
The first one is how to identify the top & bottom of a surface?

The second one is: there are two penetration or gap values in contact tool(geomtric penetration and penetration), so which one is referred to when the warning message says the initial penetration/gap is large?

Below is one row of the initial information from contact tool. And the color of this row is orange and also I received a warning about large initial penetration/gap. So could anyone explain to me how these values listed are calculated? And do the surface thickness and offset type I mentioned in the background information play any role in here?

Name: bonded-r_middle To skin
Contact Side: Contact
Type: Bonded
Status: Closed
Number of Contacting: 1308
Penetration(mm): 1.588e-012
Gap(mm):0
Geometric Penetration(mm): 1.2928
Geometric Gap (mm): 0.23277
Resulting Pinball (mm): 1.9525
Real Constant: 17