Fig. 1.

Representative plots showing indentation versus time (A) and force versus time (B). This original raw data from Chang et al. (2012) was used here to calculate the instantaneous and equilibrium moduli at each strain increment. A total of six displacement increments were applied creating a maximum indentation of 0.03 mm (30 µm) which corresponds to a strain of 57% for this sample with a thickness of 53 µm.