Studying Visco-Plasticity of Amorphous Polymers by Indentation Tests.

A constitutive model for thermoplastic polymeric materials and its finite element implementation are presented. A five-step indentation scheme was formulated to extract a complete list of the parameters in the constitutive model. Indentation tests on polymethylmethacrylate (PMMA), following the five-step and other schemes, were performed. The experimental data using the five-step scheme were used to extract all the parameters in the model. The extracted parameters were then used to predict the other experimental results. Good agreements between the experimental results and model prediction indicate that the five-step indentation scheme is a practical approach to determine the mechanical properties of thermoplastic polymers. [ABSTRACT FROM AUTHOR]