Theoretical and experimental investigation of nanoindentation of polymers

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While nanoindentation got a reliable mean for the estimation of metal properties, properties of viscoelastic polymers cannot be determined by this method in a simple way. It is our aim to model the nonlinear viscoelastic behaviour of polymers and to determine the involved model parameters from rate-dependent indentation tests. To set up the stage, real experiments are replaced by finite element simulation of the indentation tests. The obtained data are treated as input data for the parameter identification procedure in the sense of a numerical laboratory. The goal of the project is to quantify the influence of the polymer’s viscosity, friction, and adhesion between the polymer layer and the indenter tip. Furthermore it will be proofed up to which accuracy the model parameters can be reidentified from the data of the virtual experiment. Based on this experience real indentation experiments can be performed on viscoelastic materials and evaluated with respect to the model parameters. The results from the indentation tests will be compared to results obtained in uniaxial tension tests.