A Voronoi cell finite element model for the indentation of graded ceramic composites

This paper presents a numerical approach, based on the Voronoi Cell hybrid Finite Element formulation, to the evaluation of the mechanical properties of Alumina/Zirconia graded composites. The computational model is based on two main features: (i) the discretization of the domain into homogeneous regions having geometrical features similar to those of the grains in each phase and (ii) the formulation of hybrid finite elements having polygonal shape and a non linear constitutive formulation which takes into account permanent strains and thermal effects. The purpose of the computational tool is to study the mechanical behaviour of layered graded materials subjected to contact loads on the surface. The analyses have shown that a stress redistribution and a lowering of the maximum tensile stress can be obtained by introducing a proper gradient of the mechanical properties of the ceramic composite. The results have shown that the effects of the thermal residual stress field, induced by the manufacturing process, must be taken into account for a proper assessment of the mechanical behaviour of the graded ceramic composites.