Smolin A.Y.   Konovalenko I.S.   Psakhie S.  

Modelling ceramics with gel filler

Reporter: Smolin A.Y.

A numerical model of ceramic filled with gel have been developed based on the movable cellular automaton method. The response function of automata simulating ceramics corresponds to elastic-brittle body, and the function for simulating gel corresponds to elastic-plastic body with bilinear hardening. Von Mises criterion is used for breaking bonds between ceramics automata, and the two-parameter criterion of Drucker-Prager is used for automaton couples "ceramic-gel".  Coarse grain ZrO₂ (Y₂O₃) ceramics with the value of total porosity of 30% was simulated.

We studied uniaxial compression of plane samples with both empty and filled with gel pores. Sample size was 300×300 mm, the size of a cellular automaton (1 micron) corresponds to the average grain size. The pore structure is defined by two methods. The first method considers only cells of the pores, the second one considers the cells and pores of 2 microns. Pores were generated by removing a single automaton randomly (the second method) and their six nearest neighbors (first method) of the initial dense packing machines.

It is shown that in all the cases filling of porous samples with gel alters the distribution of stress concentrators in a sample, in particular making it more uniform. So the samples of the same pore structure filled with gel differ from the sampes without gel in the place of crack formation and the path of crack propagation. Thus in the samples with gel the fracture pattern is closer to one of solid body.

A comparison of simulation results with experimental data are in good qualitative agreement in the range of porosity greater than 45%. In two dimensions, this value corresponds to 30% of porosity. Thus, the model of porous ceramics filled with gel built in the framework of the movable cellular automaton method can describe the mechanical behavior and the response of the material in compression qualitatively.