Power law creep of polycarbonate by Berkovich nanoindentation

Power-law creep of polycarbonate was investigated by Berkovich indentation under three different conditions at room temperature, namely: constant displacement rate condition, constant displacement loading condition, and constant ratio of loading rate over load condition. Only the data during the loading process were analysed, and the experiments under different loading conditions gave consistent results that accorded well with theoretical prediction by dimensional analysis of indentation of power-law creep material. Material constants were characterized by curve fitting of the experimental results with theoretical equations, and the power law exponent for the power-law creep relation was found to be about 0.138 for the notably soft polycarbonate.