Fracture mechanics of porous ceramics using discrete element simulations

Abstract

The fracture behavior of highly porous ceramics is simulated using the discrete element method. A representative volume element made of spherical particles models the powder used to obtain a partially sintered ceramic material. Three-dimensional porous microstructures made of several tens of thousands of particles are then generated. Elastic force-displacement laws model the bonds formed between particles during sintering. A realistic fracture criterion, based on the local stress intensity factor associated with the bond between two particles, is also introduced. Based on these simulations, we compute the effective strength of these microstructures in tension as a function of the residual porosity. Furthermore, the introduction of a pre-crack in a sample subjected to a remote tensile stress allows the critical stress intensity factor to be calculated. Porous electrodes for electrochemical applications represent an important application field for these ceramics. Those discrete element simulations should be an effective tool for optimizing their microstructure at the submicronic length scale.