Extraction of stress–strain curves of elastic–viscoplastic solids using conical/pyramidal indentation testing with application to polymers

The increasing use of polymeric materials as thin coatings requires appropriate mechanical characterization methods at micro and nano-scale taking account of time-dependent effects. In this paper, a nanoindentation method developed initially for elastoplastic solids is extended to elasto-viscoplastic solids. It allows to determine very easily and quickly a first approximation of the stress–strain curves of Bingham–Norton elastic–viscoplastic materials. The procedure is based on the use of different indenter geometries and different loading conditions. The method is then extended to the mechanical characterization of glassy polymers in assuming a G’sell law for describing their behaviour in compression. In the last part, we apply this method to nanoindentation tests on PMMA, PS and PC samples.