On the different behaviour of porous ceramic polycrystalline materials under tension and compression stress state

摘要

The aim of the paper is to show different response of porous polycrystalline ceramic materials under tension and compression stress states. Porosity of the material is distributed inside grains and along grain boundaries. Two manners of cracks initiation due to stress concentration at the pore boundary were analysed for two considered stress states. In ceramic polycrystalline material cracks grow mainly intergranularly due to less value of the fracture surface energy of grain boundary in comparison to grain. The theoretical modelling of the material was done by mesomechanical approach with application of average procedure over the Representative Surface Element (RSE) and considering initial porosity and a set of growing cracks inside of RSE. It allows building constitutive relations in order to get comparison of the material behaviour under tension and compression.