Abstract
Indentation processes in PMMA are examined in order to test the theory developed by Puttick, Smith and Miller (1977). Ball, cone and wedge indenters of various configurations are considered and the effect of loading rate is also considered. For ball and cone indenters the effect of friction is found to be most important and corrections are made for this. By use of fractography and other methods values are assigned to the c/a ratio for various conditions. The values are found to be between 1.8 and 2.0 for ball indenters and 1.5 and 1.6 for cone indenters. Using these c/a ratios the theoretical predictions of indentation pressures are shown to be in close agreement with the experimental results for the test conditions used. For wedge indenters the model is of limited use due to changes in deformation mode with wedge angle.