Since your setup looks geometrically friendly. In your case I would perform a simulation with a finite elements analysis. For example, you could see the simulation setup in this paper: http://www.sciencedirect.com/science/article/pii/S0921509305004946

Thank you Dr. Zhang for your input. For epoxy analysis, it has been shown that Hertz does a poor prediction of modulus and O&P approach is a more accurate alternative. However, the adhesion theories are developed based on modification of Hertz modulus. Having done the nanoindentation on epoxy, the presence of permanent deformation is evident.

Thank you Dr. Guzman for your answer and the link to the paper. I am getting experimental data and I was hoping to find an approach to modify the obtained modulus.

All theories depend on the contact area of indenter during indentation. It is very critical to measure the exact contact area. Once the contact area is obtained, it is very easy to estimate the adhesion.

I worked with epoxy, and PMMA., Especially for epoxy material contact area, depends on molecular functional groups available in the structure.

Do nanoindentation with displacement control and measure the contact area. Then plug-in in appropriate theory.

 For more information go through below links.

http://onlinelibrary.wiley.com/doi/10.1002/app.43532/full

http://www.sciencedirect.com/science/article/pii/S0032386116301227