A coupled experimental/numerical approach for the modelling of the local mechanical behaviour of epoxy polymer materials

This paper presents an original coupled experimental/numerical approach for the characterisation of the local mechanical behaviour of epoxy polymer materials.The experimental approach aims at characterising the time-dependent mechanical behaviour of such materials and is based on ultra-micro indentation (UMI) and confocal interferometric microscopy (CIM) tests: the UMI load vs. displacement curve is exploited to gain some information about the short-range timescales, the CIM observation of the three-dimensional indentation prints and their evolution with time allows characterising the long-range timescales. The numerical approach provides simulation of the experimentally observed behaviour by integrating a nonlinear viscoelastic/softening polymer constitutive law within a 3D ABAQUS finite element model of the test setup. The constitutive law is modelled within the framework of the thermodynamics of irreversible processes with internal variables: the identification of the material parameters characterising the constitutive law is carried out by inverse analysis of the experimental results.