A new model for the time-dependent behaviour of polycrystalline ceramic materials with metallic inter-granular layers under tension

A novel constitutive numerical model for predicting the time-dependent mechanical response of a polycrystalline ceramic material containing finite thickness inter-granular layers is proposed. The material consists of elastic grains, whereas the inter-granular layers have visco-plastic properties. The material structure was modelled using eight-noded isotropic hexagonal finite elements both for the grains and the interfaces. The paper presents results from an investigation into the influence of the initial heterogeneity of the material on the stress and displacement distribution inside the polycrystalline material when subjected to uniaxial tension. In some parts of the polycrystalline structure, local stress concentrations can be observed both on the surface and inside the material. These can initiate defects in the form of pores, cracks, etc. In this paper, the influence of the viscosity parameter of the interface material on the overall material response is also described.