Abaqus + Skin + Shell + too low stresses

Hello, 



i am using Abaqus/Standard to simulate the contact of a ball with a flat. Up to this point the simulation is no problem and gives good results compared to the herzian theory. But within my bachelor thesis i have to add a coat (with layers) to the flat (Thickness: 0.004 mm) and analyse the influence of the coat material to the stresses. My idea is to create a skin on the plate and a shell composite section. Then i assign the skin to this section. In the field output i defined the section points to get the stresses over the thickness of the shell. 



For the plate i´m using C3D10M elements, for the Shell STRI65 elements 

- Shell Offset middle surface 

- Interaction: surface-to-surface contact (adjust only to remove overclose)
 

- Contact Property: Normal behavior, "Hard" Contact, Direct (Standard) 



My problem is, that the stresses of the shell elements are too low. If i define the same material too the shell composite section as to the flat (both steel: 210GPa, 0.3), i get a much lower level of the S11 stresses in my coat compared to the stresses in the substrate. An axissymetric model gives the same results. So what i´m doing wrong? 

It´s my first time working with FEM/Abaqus, so i would call me a beginner. 



It would be great if anyone could help me solving this problem, so i can go on with my bachelor thesis. 



Nico