Deconvolution of hardness from data obtained from nanoindentation of rough surfaces

Variation of hardness with penetration in nanoindentation of a rough surface is a compound effect of variation in asperity geometry with penetration, designated geometric effect, and genuine property gradients with depth as may exist in a near- surface zone. We simulate indentation of a rough surface numerically to elucidate the geometric effects and validate it by some model "macro" experiments. Finally, we formulate a general framework to deconvolute genuine property variation by normalizing the measured hardness with the geometric effect