A new method for determining the strain energy release rate of an interface via force-depth data of nanoindentation tests

Indentation forces, including constant rate and oscillating mode, were applied to SiO2/Si and diamond-like carbon ( DLC)/Si specimens. A two-stage behavior was exhibited in the force-depth results after delamination occurred. When the depth was smaller than the threshold value, a linear load-depth relationship was exhibited because the debonded film was suspended over the substrate. Membrane theory was applied to analyze the deflection of the suspended film, and thus the in-plane stress exhibited in the debonded film was evaluated. Through the proposed method, the strain energy release rate of the interface can be directly evaluated by analyzing the force-depth data of the indentation tests.