A Study on Strength Distribution and Size Effect of Ceramics by Computer-simulated Experiments

Abstract

In order to investigate the change of strength of ceramics due to the size effect, the strength distribution was simulated by the Monte-Carlo method. The tensile strength, 3- and 4-point bending strength of four kinds of specimens of different sizes were calculated, by using the model of specimens with a number of penny-shaped inner cracks of which diameters followed the prescribed distribution. The strength obtained was plotted on the Weibull probability papers and represented by the 2-parameter Weibull distribution. As some experimental data had indicated, the Weibull modulus had a tendency to increase as the effective size decreased. It became clear that this tendency was caused by the existence of the upper limit of crack strength. The strength distribution function for this model was also expressed and compared with the simulation results. Although the Weibull plot of that function was slightly concave, it showed good agreement with the simulation results.
Furthermore, the relation between the mean strength and the effective volume was discussed, using the Weibull statistics. As a result, it was indicated that the Weibull statistics could not explain the change of strength due to the size effect satisfactorily.