Nanoindentation analysis methods examined with finite element simulations

Quantitative mechanical properties were obtained from simulated nanoindentation load–depth curves using three analysis methods. Unloading curve fits for stiffness, depth and contact area gave reliable and relatively accurate values of elastic modulus and hardness, though inaccuracies occurred in some cases. Work of indentation analysis was effective for finding the ratio of hardness to reduced elastic modulus, but a large discrepancy occurred in one case. Fitting the loading curves with parabolas gave good fits to the simulated curves. Accurate ratios of elastic modulus to hardness were obtained for some of the loading fits, though others were inaccurate. Each method has specific strengths and weaknesses, but crucially, they all consider different aspects of the load–depth data. This means the methods are potentially complementary and a single, combined analysis may be possible and beneficial in obtaining accurate values.