Nanoindentation is an effective approach for measuring mechanical properties of
nanoscale films coated on substrates, yet results obtained through the classic
Oliver–Pharr model require additional consideration due to the existence
of a “substrate effect” when the film is much more compliant than
the substrate. In this study, different models for removing this substrate
effect are compared, with focus on the Gao model, the Saha–Nix model, and
the Hay model and the use of a direct finite element (FE) approach is discussed.
Validity of these models is examined using load–displacement data
obtained from simulated indentation of an elastic–plastic film in FEs. It
is found that the performance of the analytical models varies significantly with
different testing parameters, including ratio between film modulus and substrate
indenting ratio (hmax/film thickness), and yield
strain. Choices of using a nanoindentation model to process experimental data
should be made according to estimated indentation depth and modulus difference
between film and substrate. An example of applying substrate removal models to
experimental data is also shown.