On the variation of mechanical parameters obtained from spherical depth sensing indentation

International audienceWe present an analysis of spherical depth sensing indentation. In thispaper, the Oliver and Pharr methodology is applied to the experimentalload-displacement curves and those obtained numerically for determininghardness H and Young’s modulus E. The numerical results are obtained byBEM code. The observed variations with respect to load of the elastic modulusand the hardness as obtained by the Oliver and Pharr methodology arecorrelated with plastic zone shape. In the case of isotropic homogeneousmaterial, numerical results show that almost constant elastic modulus isobtained when the plastic zone has developed up to the free surface. In the caseof elastic (very hard) coating on an elastic perfectly plastic substrate, plasticdeformation in the latter is followed by reverse plastic flow during unloadingleading to a decrease in the calculated value of hardnes