Prediction of Homogenized Elastic Moduli of Ceramics Using Polycrystalline Grain Model (Influence of Two-Dimensional Microstructural Model Size)
Yoshihisa SAKAIDA, Koji Sato · TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A · 2003
Microstructures of polycrystalline Al2O3, Zro2 and Al2O3-ZrO2 ceramics were modeled as two-dimensional heterogeneous bodies composed of geometric Al2O3 and ZrO2 grains. The crystallographic 3D-directions of each grain were assumed to be randomly distributed. Elastic properties of grain were derived from elastic stiffnesses, cij, of single crystal Al2O3 and ZrO2. In calculation, some square plates with a unit thickness were cut from the initial grain models. A simulation method was developed to predict homogenized elastic moduli of models using a finite element method. An influence of the microstructural model size on apparent elastic moduli was examined. Next, actual microstructural models that were traced the SEM micrographs of samples were used in same calculation. And then, the optimum model size was determined by comparing calculated elastic moduli to experimental data measured by a pulse-echo method. As a result, the scattering of apparent elastic moduli, such as Young's modulus, of both models including Al2O3 grains varies narrowly with increasing model size. While, the deviation of apparent elastic moduli for actual model is wider than that of geometric model on the same model size. The number of Al2O3 grains within the optimum model size was found to be about more than 400, in which the scattering of apparent elastic moduli is below the ±1% deviation of the mean value of model samples.