Finer-Scale Characterization and Scale Transition of Viscoelastic Properties within the Multiscale Framework of Material Description

摘要

Recent progress in both finer-scale experimentation (atomic force microscopy, nanoindentation, …) and theoretical and numerical upscaling schemes provides the basis for the development of so-called multiscale models, taking finer scales of observation into account. Hereby, chemical, physical, and mechanical processes taking place at finer scales can be considered and their effect on the macroscopic material performance is obtained via appropriate upscaling schemes. The success of multiscale models is strongly linked to the proper identification of material properties at finer scales, serving as input for the upscaling schemes. In this paper, extraction of material parameters by means of the nanoindentation technique is presented. Whereas the extraction of elastic parameters dates back to the 1990s, the focus of this paper is on the extraction of viscoelastic properties. Hereby, the experimental data are compared with the respective analytical solution for the mathematical problem of a rigid indenter penetrating a viscoelastic medium, giving access to the viscoelastic material properties at finer scales. Finally, continuum micromechanics is employed for upscaling of the identified viscoelastic parameters. The proposed identification and upscaling scheme is applied to cement-based and bituminous mixtures, both characterized by a matrix-inclusion morphology, with cement and bitumen, respectively, serving as binder material.