Approches multi-échelles des composites granulaires avec effets d'interface : applications aux nanocomposites et composites cimentaires

摘要

Modelling composite media in view of determining its effective mechanical behaviour has been the topic of a large number of research papers. Some analytical and numerical models that can be found in the scientific literature on this topic take into account the interface effects that can arise at inclusions' boundaries. These interfaces have a major influence on the mechanical properties of composites according to some researchers. However, the models considering them are limited to spherical and cylindrical inclusions. In this work, several multi-scale approaches and models are developed to consider interface effects in the determination of the effective elastic and poroelastic properties and the failure mechanisms of granular composites. These models are performed on both spherical and ellipsoidal shapes of inclusions. The latter has led us to investigate an anisotropic inter-granular failure in granular media. The failure models developed in this work are applied to the microstructure of C-S-H gels (a cement paste hydrate) in order to improve the existing models on cement paste failure. The predictions of these improved models are compared to experimental data on the compressive strength of cement pastes