A new technique to determine the true projected contact area by nanoindentation is presented. It requires combining two models used normally to determine the representative stress and strain from nanoindentation parameters. Consequently, it does not require any model classically used to calculate the projected contact area. The method requires performing indentation on the same sample with two indenter tips with different geometries (Berkovich tip and a tetrahedral tip with a semi-angle equal to 50°). The method was applied to three samples: glass, PMMA, and 100C6 steel. The projected contact area obtained by this model was accurate in all cases.
Guillonneau, G., Kermouche, G., Bergheau, J. M., & Loubet, J. L. (2015). A new method to determine the true projected contact area using nanoindentation testing. Comptes Rendus - Mecanique, 343(7–8), 410–418. https://doi.org/10.1016/j.crme.2015.06.004