An Influence of Initial Porosity on Damage Process in Semi-brittle Polycrystalline Ceramics under Compression

Abstract

The initial porosity inside ceramics strongly influences the material response to applied mechanical load. In the paper two types of porosity were considered: distributed inside grains and along grain boundaries. Both types of porosity influence elastic material properties (compliance tensor S_l jkl). The pores distributed along grain boundary lead to significant crack resistance reduction in that part of the material. These local weakening places create preferential conditions for microcracks growth, which are responsible for internal damage process in macro-scale. The proposed theory was illustrated by uniaxial compression loading process of polycrystalline magnesium oxide sample.