HDPE Properties Evaluation via Instrumented Indentation: Experimental and Computer Simulation Approach

The paper analyzes the process of indentation of polymeric materials with a spherical indenter. The loading diagrams P(h) obtained experimentally and by means of finite element method (FEM) are analyzed. The material under study was high-density polyethylene (HDPE) of PE100 grade, taken from a pipeline for gas distribution systems. The aim of the work was to determine the parameters of the computer model, taking into account hardening and creep processes when verifying P(h) diagrams with experimental studies. The influence of variation of the parameters of the calculation formulas on the reliability of the simulation results was analyzed. The results of the calculation of mechanical properties of material on the basis of P(h) diagrams by the Oliver–Pharr method for model and experimental diagrams were compared. The possibility of using computer modeling for the analysis of instrumented indentation processes is demonstrated, since the results revealed the convergence of the elastic modulus of 1078 GPa for FEM and 1083 GPa for the experiment. The conformity of the Oliver–Pharr method for determining the contact depth is also shown, which differed from the model geometry by only 2.3%. Simulation of the indentation process using the Norton model via FEM, as well as determining the parameters of the material deformation function while taking creep into account, makes it possible to describe the process of contact interaction and shows good agreement with experimental data.