What tension/compression loads does aircraft wing skin experience?

Ok so thinking about aircraft like the 787, which have some quite drastic wing flex (upper image), I was wondering what the loads are that are placed on the skin on the the upper and lower surfaces of the wing (not considering torsion from control surfaces etc...) - considering tension and compression only.

So naturally, one would assume that the upper skin panels experiences compression, and the lower skin panels, tension due to the different radii of rotation they both follow. However, does, for example the lower surface of the upper wing skin experience tension, not compression, due to the material thickness (I'm thinking about the principle in the lower image).

In that case, the strain distribution can be seen in the following image (see below $$\varepsilon_c$$. The only difference is that the lift has the opposite direction to the load in the image. You can see that the top distribution is entirely in tension and the bottom skin is totally in compression.